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Pulmonary surfactant serves as a barrier to respiratory epithelium but can also regulate airway smooth muscle (ASM) tone. Surfactant (SF) relaxes contracted ASM, similar to β 2 -agonists, anticholinergics, nitric oxide, and prostanoids. The exact mechanism of surfactant relaxation and whether surfactant relaxes hyperresponsive ASM remains unknown. Based on previous research, relaxation requires an intact epithelium and prostanoid synthesis. We sought to examine the mechanisms by which surfactant causes ASM relaxation. Organ bath measurements of isometric tension of ASM of guinea pigs in response to exogenous surfactant revealed that surfactant reduces tension of healthy and hyperresponsive tracheal tissue. The relaxant effect of surfactant was reduced if prostanoid synthesis was inhibited and/or if prostaglandin E 2 -related EP 2 receptors were antagonized. Atomic force microscopy revealed that human ASM cells stiffen during contraction and soften during relaxation. Surfactant softened ASM cells, similarly to the known bronchodilator prostaglandin E 2 (PGE 2 ) and the cell softening was abolished when EP 4 receptors for PGE 2 were antagonized. Elevated levels of PGE 2 were found in cultures of normal human bronchial epithelial cells exposed to pulmonary surfactant. We conclude that prostaglandin E 2 and its EP 2 and EP 4 receptors are likely involved in the relaxant effect of pulmonary surfactant in airways., (© 2024 The Author(s). Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Mitochondria play a crucial role in maintaining Ca 2+ homeostasis in cells. Due to the critical regulatory role of the products of oxidative and non-oxidative metabolism of L-arginine, it is essential to clarify their effect on Ca 2+ transport in smooth muscle mitochondria. Experiments were performed on the uterine myocytes of rats and isolated mitochondria. The possibility of NO synthesis by mitochondria was demonstrated by confocal microscopy and spectrofluorimetry methods using the NO-sensitive fluorescent probe DAF-FM and Mitotracker Orange CM-H2TMRos. It was shown that 50 μM L-arginine stimulates the energy-dependent accumulation of Ca 2+ in mitochondria using the fluorescent probe Fluo-4 AM. A similar effect occurred when using nitric oxide donors 100 μM SNP, SNAP, and sodium nitrite (SN) directly. The stimulating effect was eliminated in the presence of the NO scavenger C-PTIO. Nitric oxide reduces the electrical potential in mitochondria without causing them to swell. The stimulatory effect of spermine on the accumulation of Ca 2+ by mitochondria is attributed to the enhancement of NO synthesis, which was demonstrated with the use of C-PTIO, NO-synthase inhibitors (100 μM NA and L-NAME), as well as by direct monitoring of NO synthesis fluorescent probe DAF-FM. A conclusion was drawn about the potential regulatory effect of the product of the oxidative metabolism of L-arginine - NO on the transport of Ca 2+ in the mitochondria of the myometrium, as well as the corresponding effect of the product of non-oxidative metabolism -spermine by increasing the synthesis of NO in these subcellular structures., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hanna Danylovych reports financial support was provided by Palladin Institute of Biochemistry National Academy of Sciences of Ukraine. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Exposure to particulate matter (PM 10 ) can induce respiratory diseases that are closely related to bronchial hyperresponsiveness. However, the involved mechanism remains to be fully elucidated. This study aimed to demonstrate the effects of PM 10 on the acetylcholine muscarinic 3 receptor (CHRM3) expression and the role of the ERK1/2 pathway in rat bronchial smooth muscle. A whole-body PM 10 exposure system was used to stimulate bronchial hyperresponsiveness in rats for 2 and 4 months, accompanied by MEK1/2 inhibitor U0126 injection. The whole-body plethysmography system and myography were used to detect the pulmonary and bronchoconstrictor function, respectively. The mRNA and protein levels were determined by Western blotting, qPCR, and immunofluorescence. Enzyme-linked immunosorbent assay was used to detect the inflammatory cytokines. Compared with the filtered air group, 4 months of PM 10 exposure significantly increased CHRM3-mediated pulmonary function and bronchial constriction, elevated CHRM3 mRNA and protein expression levels on bronchial smooth muscle, then induced bronchial hyperreactivity. Additionally, 4 months of PM 10 exposure caused an increase in ERK1/2 phosphorylation and increased the secretion of inflammatory factors in bronchoalveolar lavage fluid. Treatment with the MEK1/2 inhibitor, U0126 inhibited the PM 10 exposure-induced phosphorylation of the ERK1/2 pathway, thereby reducing the PM 10 exposure-induced upregulation of CHRM3 in bronchial smooth muscle and CHRM3-mediated bronchoconstriction. U0126 could rescue PM 10 exposure-induced pathological changes in the bronchus. In conclusion, PM 10 exposure can induce bronchial hyperresponsiveness in rats by upregulating CHRM3, and the ERK1/2 pathway may be involved in this process. These findings could reveal a potential therapeutic target for air pollution induced respiratory diseases., Competing Interests: Declaration of competing interest The authors have no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Gut motility undergoes a switch from myogenic to neurogenic control in late embryonic development. Here, we report on the electrical events that underlie this transition in the enteric nervous system, using the GCaMP6f reporter in neural crest cell derivatives. We found that spontaneous calcium activity is tetrodotoxin (TTX) resistant at stage E11.5, but not at E18.5. Motility at E18.5 was characterized by periodic, alternating high- and low-frequency contractions of the circular smooth muscle; this frequency modulation was inhibited by TTX. Calcium imaging at the neurogenic-motility stages E18.5-P3 showed that Ca V 1.2-positive neurons exhibited spontaneous calcium activity, which was inhibited by nicardipine and 2-aminoethoxydiphenyl borate (2-APB). Our protocol locally prevented muscle tone relaxation, arguing for a direct effect of nicardipine on enteric neurons, rather than indirectly by its relaxing effect on muscle. We demonstrated that the ENS was mechanosensitive from early stages on (E14.5) and that this behaviour was TTX and 2-APB resistant. We extended our results on L-type channel-dependent spontaneous activity and TTX-resistant mechanosensitivity to the adult colon. Our results shed light on the critical transition from myogenic to neurogenic motility in the developing gut, as well as on the intriguing pathways mediating electro-mechanical sensitivity in the enteric nervous system. HIGHLIGHTS: What is the central question of this study? What are the first neural electric events underlying the transition from myogenic to neurogenic motility in the developing gut, what channels do they depend on, and does the enteric nervous system already exhibit mechanosensitivity? What is the main finding and its importance? ENS calcium activity is sensitive to tetrodotoxin at stage E18.5 but not E11.5. Spontaneous electric activity at fetal and adult stages is crucially dependent on L-type calcium channels and IP 3 R receptors, and the enteric nervous system exhibits a tetrodotoxin-resistant mechanosensitive response. Abstract figure legend Tetrodotoxin-resistant Ca 2+ rise induced by mechanical stimulation in the E18.5 mouse duodenum., (© 2024 The Author(s). Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Multidrug resistance proteins type 4 (MRP4) and 5 (MRP5) play pivotal roles in the transport of cyclic nucleotides in various tissues. However, their specific functions within the lower urinary tract remain relatively unexplored. This study aimed to investigate the effect of pharmacological inhibition of MRPs on cyclic nucleotide signaling in isolated pig bladder. The relaxation responses of the bladder were assessed in the presence of the MRP inhibitor, MK571. The temporal changes in intra- and extracellular levels of cAMP and cGMP in stimulated tissues were determined by mass spectrometry. The gene ( ABCC4 ) and protein (MRP4) expression were also determined. MK571 administration resulted in a modest relaxation effect of approximately 26% in carbachol-precontracted bladders. The relaxation induced by phosphodiesterase inhibitors such as cilostazol, tadalafil, and sildenafil was significantly potentiated in the presence of MK571. In contrast, no significant potentiation was observed in the relaxation induced by substances elevating cAMP levels or stimulators of soluble guanylate cyclase. Following forskolin stimulation, both intracellular and extracellular cAMP concentrations increased by approximately 15.8-fold and 12-fold, respectively. Similarly, stimulation with tadalafil + BAY 41-2272 resulted in roughly 8.2-fold and 3.4-fold increases in intracellular and extracellular cGMP concentrations, respectively. The presence of MK571 reduced only the extracellular levels of cGMP. This study reveals the presence and function of MRP4 transporters within the porcine bladder and paves the way for future research exploring the role of this transporter in both underactive and overactive bladder disorders. NEW & NOTEWORTHY This study investigates the impact of pharmacological inhibition of MRP4 and MRP5 transporters on cyclic nucleotide signaling in isolated pig bladders. MK571 administration led to modest relaxation, with enhanced effects observed in the presence of phosphodiesterase inhibitors. However, substances elevating cAMP levels remained unaffected. MK571 selectively reduced extracellular cGMP levels. These findings shed light on the role of MRP4 transporters in the porcine bladder, opening avenues for further research into bladder disorders.

High serum estrogen concentrations are associated with asthma development and severity, suggesting a link between estradiol and airway hyperresponsiveness (AHR). 17β-estradiol (E2) has non-genomic effects via Ca 2+ regulatory mechanisms; however, its effect on the plasma membrane Ca 2+ -ATPases (PMCA1 and 4) and sarcoplasmic reticulum Ca 2+ -ATPase (SERCA) is unknown. Hence, in the present study, we aim to demonstrate if E2 favors AHR by increasing intracellular Ca 2+ concentrations in guinea pig airway smooth muscle (ASM) through a mechanism involving Ca 2+ -ATPases. In guinea pig ASM, Ca 2+ microfluorometry, muscle contraction, and Western blot were evaluated. Then, we performed molecular docking analysis between the estrogens and Ca 2+ ATPases. In tracheal rings, E2 produced AHR to carbachol. In guinea pig myocytes, acute exposure to physiological levels of E2 modified the transient Ca 2+ peak induced by caffeine to a Ca 2+ plateau. The incubation with PMCA inhibitors (lanthanum and carboxyeosin, CE) partially reversed the E2-induced sustained plateau in the caffeine response. In contrast, cyclopiazonic acid (SERCA inhibitor), U-0126 (an inhibitor of ERK 1/2), and choline chloride did not modify the Ca 2+ plateau produced by E2. The mitochondrial uniporter activity and the capacitative Ca 2+ entry were unaffected by E2. In guinea pig ASM, Western blot analysis demonstrated PMCA1 and PMCA4 expression. The results from the docking modeling demonstrate that E2 binds to both plasma membrane ATPases. In guinea pig tracheal smooth muscle, inhibiting the PMCA with CE, induced hyperresponsiveness to carbachol. 17β-estradiol produces hyperresponsiveness by inhibiting the PMCA in the ASM and could be one of the mechanisms responsible for the increase in asthmatic crisis in women., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A thin film of pulmonary surfactant lines the surface of the airways and alveoli, where it lowers the surface tension in the peripheral lungs, preventing collapse of the bronchioles and alveoli and reducing the work of breathing. It also possesses a barrier function for maintaining the blood-gas interface of the lungs and plays an important role in innate immunity. The surfactant film covers the epithelium lining both large and small airways, forming the first line of defense between toxic airborne particles/pathogens and the lungs. Furthermore, surfactant has been shown to relax airway smooth muscle (ASM) after exposure to ASM agonists, suggesting a more subtle function. Whether surfactant masks irritant sensory receptors or interacts with one of them is not known. The relaxant effect of surfactant on ASM is absent in bronchial tissues denuded of an epithelial layer. Blocking of prostanoid synthesis inhibits the relaxant function of surfactant, indicating that prostanoids might be involved. Another possibility for surfactant to be active, namely through ATP-dependent potassium channels and the cAMP-regulated epithelial chloride channels [cystic fibrosis transmembrane conductance regulators (CFTRs)], was tested but could not be confirmed. Hence, this review discusses the mechanisms of known and potential relaxant effects of pulmonary surfactant on ASM. This review summarizes what is known about the role of surfactant in smooth muscle physiology and explores the scientific questions and studies needed to fully understand how surfactant helps maintain the delicate balance between relaxant and constrictor needs.

The synthesized compound 1-(2-chlorophenyl) 6-7-dimethoxy-3-methyl-3,4-dihydroisoquinoline (DIQ) was investigated as a biological agent. Its potential to affect muscle contractility was predicted through in silico PASS analysis. Based on the in silico analysis, its capabilities were experimentally investigated. The study aimed to investigate the effects of DIQ on the ex vivo spontaneous contractile activity (CA) of smooth muscle (SM) tissue. DIQ was observed to reduce the strength of Ca 2+ -dependent contractions in SM preparations (SMP), possibly by increasing cytosolic Ca 2+ levels through the activation of a voltage-gated L-type Ca 2+ channel. DIQ potently affected calcium currents by modulating the function of muscarinic acetylcholine receptors (mAChRs) and 5-hydroxytryptamine (5-HT) receptors at a concentration of 50 μM. Immunohistochemical tests showed a 47% reduction in 5-HT 2A and 5-HT 2B receptor activity in SM cells and neurons in the myenteric plexus (MP), further confirming the effects of DIQ. Furthermore, a significant inhibition of neuronal activity was observed when the compound was co-administered with 5-HT to SM tissues. The conducted experiments confirm the ability of the isoquinoline analog to act as a physiologically active molecule to control muscle contractility and related physiological processes.

Determining the female animal cycle is crucial in preclinical studies and animal husbandry. Changes in hormone levels during the cycle affect physiological responses, including altered contractility of the visceral smooth muscle. The study aimed to identify estrus and anestrus using smooth muscle electromyographic (SMEMG) measurements, in vivo fluorescent imaging (IVIS) and in vitro organ contractility of the uterus and cecum. The study involved sexually mature female Sprague-Dawley rats, aged 10-12 weeks. The rats received a daily injection of cetrorelix acetate solution for 7 days, while another group served as the control. The animals were subjected to gastrointestinal and myometrial SMEMG. The change in αvβ3 integrin activity was measured with IVIS in the abdominal cavity. Contractility studies were performed in isolated organ baths using dissected uterus and cecum samples. Plasma samples were collected for hormone level measurements. A 3-fold increase in spontaneous contraction activity was detected in SMEMG measurements, while a significant decrease in αvβ3 integrin was measured in the IVIS imaging procedure. Cetrorelix reduced the level of LH and the progesterone / estradiol ratio, increased the spontaneous activity of the cecum rings, and enhanced KCl-evoked contractions in the uterus. We found a significant change in the rate of SMEMG signals, indicating simultaneous increases in the contraction of the cecum and the non-pregnant uterus, as evidenced by isolated organ bath results. Fluorescence imaging showed high levels of uterine αvβ3 integrin during the proestrus-estrus phase, but inhibiting the sexual cycle reduced fluorescence activity. Based on the results, the SMEMG and IVIS imaging methods are suitable for detecting estrus phase alterations in rats., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Szucs et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Shortening of airway smooth muscle and bronchoconstriction are pathognomonic for asthma. Airway shortening occurs through calcium-dependent activation of myosin light chain kinase, and RhoA-dependent calcium sensitization, which inhibits myosin light chain phosphatase. The mechanism through which pro-contractile stimuli activate calcium sensitization is poorly understood. Our review of the literature suggests that pro-contractile G protein coupled receptors likely signal through G 12/13 to activate RhoA and mediate calcium sensitization. This hypothesis is consistent with the effects of pro-contractile agonists on RhoA and Rho kinase activation, actin polymerization and myosin light chain phosphorylation. Recognizing the likely role of G 12/13 signaling in the pathophysiology of asthma rationalizes the effects of pro-contractile stimuli on airway hyperresponsiveness, immune activation and airway remodeling, and suggests new approaches for asthma treatment., (© 2024. The Author(s).)

Background: The immunomodulatory imide drugs (IMiDs) thalidomide, lenalidomide and pomalidomide may exhibit therapeutic efficacy in the prostate. In lower urinary tract symptoms (LUTS), voiding and storage disorders may arise from benign prostate hyperplasia, or overactive bladder. While current therapeutic options target smooth muscle contraction or cell proliferation, side effects are mostly cardiovascular. Therefore, we investigated effects of IMiDs on human detrusor and porcine artery smooth muscle contraction, and growth-related functions in detrusor smooth muscle cells (HBdSMC)., Methods: Cell viability was assessed by CCK8, and apoptosis and cell death by flow cytometry in cultured HBdSMC. Contractions of human detrusor tissues and porcine interlobar and coronary arteries were induced by contractile agonists, or electric field stimulation (EFS) in the presence or absence of an IMID using an organ bath. Proliferation was assessed by EdU assay and colony formation, cytoskeletal organization by phalloidin staining, RESULTS: Depending on tissue type, IMiDs inhibited cholinergic contractions with varying degree, up to 50 %, while non-cholinergic contractions were inhibited up to 80 % and 60 % for U46619 and endothelin-1, respectively, and EFS-induced contractions up to 75 %. IMiDs reduced viable HBdSM cells in a time-dependent manner. Correspondingly, proliferation was reduced, without showing pro-apoptotic effects. In parallel, IMiDs induced cytoskeletal disorganization., Conclusions: IMiDs exhibit regulatory functions in various smooth muscle-rich tissues, and of cell proliferation in the lower urinary tract. This points to a novel drug class effect for IMiDs, in which the molecular mechanisms of action of IMiDs merit further consideration for the application in LUTS., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Thomas Kolben holds stock of Roche AG and a relative is employed at Bayer AG. The other authors have no conflict of interest to declare., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Aims: The nitric oxide (NO•)/soluble guanylate cyclase/cyclic-GMP (cGMP) signaling pathway is ubiquitous and regulates several functions in physiological systems as diverse as the vascular, nervous, and renal systems. However, its roles in determining normal and abnormal lower urinary tract functions are unclear. The aim was to identify potential therapeutic targets associated with this pathway to manage lower urinary tract functional disorders., Methods: This review summarizes a workshop held under the auspices of ICI-RS with a view to address these questions., Results: Four areas were addressed: NO• signaling to regulate neurotransmitter release to detrusor smooth muscle; its potential dual roles in alleviating and exacerbating inflammatory pathways; its ability to act as an antifibrotic mediator; and the control by nitrergic nerves of lower urinary tract vascular dynamics and the contractile performance of muscular regions of the bladder wall. Central to much of the discussion was the role of the NO• receptor, soluble guanylate cyclase (sGC) in regulating the generation of the enzyme product, the second messenger cGMP. The redox state of sGC is crucial in determining its enzymic activity and the role of a class of novel agents, sGC activators, to optimize activity and to potentially alleviate the consequences of lower urinary tract disorders was highlighted. In addition, the consequences of a functional relationship between nitrergic and sympathetic nerves to regulate vascular dynamics was discussed., Conclusions: Several potential NO•-dependent drug targets in the lower urinary tract were identified that provide the basis for future research and translation to clinical trials., (© 2023 The Authors. Neurourology and Urodynamics published by Wiley Periodicals LLC.)

6-Cyanodopamine is a novel catecholamine released from rabbit isolated heart. However, it is not known whether this catecholamine presents any biological activity. Here, it was evaluated whether 6-cyanodopamine (6-CYD) is released from rat vas deferens and its effect on this tissue contractility. Basal release of 6-CYD, 6-nitrodopamine (6-ND), 6-bromodopamine, 6-nitrodopa, and 6-nitroadrenaline from vas deferens were quantified by LC-MS/MS. Electric-field stimulation (EFS) and concentration-response curves to noradrenaline, adrenaline, and dopamine of the rat isolated epididymal vas deferens (RIEVD) were performed in the absence and presence of 6-CYD and /or 6-ND. Expression of tyrosine hydroxylase was assessed by immunohistochemistry. The rat isolated vas deferens released significant amounts of both 6-CYD and 6-ND. The voltage-gated sodium channel blocker tetrodotoxin had no effect on the release of 6-CYD, but it virtually abolished 6-ND release. 6-CYD alone exhibited a negligible RIEVD contractile activity; however, at 10 nM, 6-CYD significantly potentiated the noradrenaline- and EFS-induced RIEVD contractions, whereas at 10 and 100 nM, it also significantly potentiated the adrenaline- and dopamine-induced contractions. The potentiation of noradrenaline- and adrenaline-induced contractions by 6-CYD was unaffected by tetrodotoxin. Co-incubation of 6-CYD (100 pM) with 6-ND (10 pM) caused a significant leftward shift and increased the maximal contractile responses to noradrenaline, even in the presence of tetrodotoxin. Immunohistochemistry revealed the presence of tyrosine hydroxylase in both epithelial cell cytoplasm of the mucosae and nerve fibers of RIEVD. The identification of epithelium-derived 6-CYD and its remarkable synergism with catecholamines indicate that epithelial cells may regulate vas deferens smooth muscle contractility., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Transient receptor potential vanilloid 1 (TRPV1) is a calcium-permeable ion channel that is gated by the pungent constituent of red chili pepper, capsaicin, and by related chemicals from the group of vanilloids, in addition to noxious heat. It is expressed mostly in sensory neurons to act as a detector of painful stimuli produced by pungent chemicals and high temperatures. Although TRPV1 is also found outside the sensory nervous system, its expression and function in the bladder detrusor smooth muscle (DSM) remain controversial. Here, by using Ca 2+ imaging and patch clamp on isolated rat DSM cells, in addition to tensiometry on multicellular DSM strips, we show that TRPV1 is expressed functionally in only a fraction of DSM cells, in which it acts as an endoplasmic reticulum Ca 2+ -release channel responsible for the capsaicin-activated [Ca 2+ ] i rise. Carbachol-stimulated contractions of multicellular DSM strips contain a TRPV1-dependent component, which is negligible in the circular DSM but reaches ≤50% in the longitudinal DSM. Activation of TRPV1 in rat DSM during muscarinic cholinergic stimulation is ensured by phospholipase A 2 -catalysed derivation of arachidonic acid and its conversion by lipoxygenases to eicosanoids, which act as endogenous TRPV1 agonists. Immunofluorescence detection of TRPV1 protein in bladder sections and isolated DSM cells confirmed both its preferential expression in the longitudinal DSM sublayer and its targeting to the endoplasmic reticulum. We conclude that TRPV1 is an essential contributor to the cholinergic contraction of bladder longitudinal DSM, which might be important for producing spatial and/or temporal anisotropy of bladder wall deformation in different regions during parasympathetic stimulation. KEY POINTS: The transient receptor potential vanilloid 1 (TRPV1) heat/capsaicin receptor/channel is localized in the endoplasmic reticulum membrane of detrusor smooth muscle (DSM) cells of the rat bladder, operating as a calcium-release channel. Isolated DSM cells are separated into two nearly equal groups, within which the cells either show or do not show TRPV1-dependent [Ca 2+ ] i rise. Carbachol-stimulated, muscarinic ACh receptor-mediated contractions of multicellular DSM strips contain a TRPV1-dependent component. This component is negligible in the circular DSM but reaches ≤50% in longitudinal DSM. Activation of TRPV1 in rat DSM during cholinergic stimulation involves phospholipase A 2 -catalysed derivation of arachidonic acid and its conversion by lipoxygenases to eicosanoids, which act as endogenous TRPV1 agonists., (© 2024 The Authors. The Journal of Physiology © 2024 The Physiological Society.)

Introduction: To investigate the in vitro effect of diclofenac on tubal smooth muscle as an alternative to hyoscine-N-butyl bromide, which is used for premedication before hysterosalpingography (HSG)., Material and Methods: Fallopian tubes were retrieved from seven healthy women after bilateral tubal ligation and in vitro contractility and histological studies were conducted using tissue bath and immunohistochemistry., Results: Diclofenac sodium and hyoscine-N-butyl bromide did not significantly change the basal mean tension; however, they decreased the contractions induced by potassium chloride (KCl). The relaxant effect of diclofenac sodium and hyoscine-N-butyl bromide was not statistically significantly different. The presence of cyclooxygenase (COX)-2 enzyme in the fallopian tube was demonstrated by immunohistochemical studies., Conclusions: The in vitro relaxant effect of diclofenac sodium on the fallopian tube is similar to hyoscine-N-butyl bromide. Diclofenac may have the potential to be used as an alternative to hyoscine-N-butyl bromide in premedication in HSG., (© 2024 The Author(s). Basic & Clinical Pharmacology & Toxicology published by John Wiley & Sons Ltd on behalf of Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

G-protein-coupled receptors (GPCRs) belonging to the type 2 taste receptors (TAS2Rs) family are predominantly present in taste cells to allow the perception of bitter-tasting compounds. TAS2Rs have also been shown to be expressed in human airway smooth muscle (ASM), and TAS2R agonists relax ASM cells and bronchodilate airways despite elevating intracellular calcium. This calcium "paradox" (calcium mediates contraction by pro-contractile Gq-coupled GPCRs) and the mechanisms by which TAS2R agonists relax ASM remain poorly understood. To gain insight into pro-relaxant mechanisms effected by TAS2Rs, we employed an unbiased phosphoproteomic approach involving dual-mass spectrometry to determine differences in the phosphorylation of contractile-related proteins in ASM following the stimulation of cells with TAS2R agonists, histamine (an agonist of the Gq-coupled H1 histamine receptor) or isoproterenol (an agonist of the Gs-coupled β 2 -adrenoceptor) alone or in combination. Our study identified differential phosphorylation of proteins regulating contraction, including A-kinase anchoring protein (AKAP)2, AKAP12, and RhoA guanine nucleotide exchange factor (ARHGEF)12. Subsequent signaling analyses revealed RhoA and the T853 residue on myosin light chain phosphatase (MYPT)1 as points of mechanistic divergence between TAS2R and Gs-coupled GPCR pathways. Unlike Gs-coupled receptor signaling, which inhibits histamine-induced myosin light chain (MLC)20 phosphorylation via protein kinase A (PKA)-dependent inhibition of intracellular calcium mobilization, HSP20 and ERK1/2 activity, TAS2Rs are shown to inhibit histamine-induced pMLC20 via inhibition of RhoA activity and MYPT1 phosphorylation at the T853 residue. These findings provide insight into the TAS2R signaling in ASM by defining a distinct signaling mechanism modulating inhibition of pMLC20 to relax contracted ASM., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Objectives: Nocturia with or without asthma is one of the aging diseases. Desmopressin has been used as a nasal spray for patients who are suffering from nocturia. This study determined the effects of desmopressin on isolated tracheal smooth muscle in vitro . Methods: We evaluated desmopressin's efficiency on isolated rat tracheal smooth muscle. Desmopressin was evaluated for the following effects on tracheal smooth muscle: (1) effect on resting tension; (2) effect on contraction brought on by parasympathetic mimetic 10 -6 M methacholine; and (3) effect on electrically produced tracheal smooth muscle contractions. Results: As the concentration grew, desmopressin by itself had no impact on the trachea's baseline tension. Addition of desmopressin at doses of 10 -5 M or above elicited a significant relaxation response to 10 -6 M methacholine-induced contraction. Desmopressin could also inhibit spike contraction of the trachea induced by electrical field. Conclusion: According to this study, desmopressin at high quantities may prevent the trachea's parasympathetic activity. Due to its ability to block parasympathetic activity and lessen the contraction of the tracheal smooth muscle brought on by methacholine, Desmopressin nasal spray might help nocturia sufferers experience fewer asthma attacks., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Eight pig tracheal strips were stimulated to contract with log increments of methacholine from 10 -8 to 10 -5 M. For each strip, the concentration-response was repeated four times in a randomized order to measure isometric force, isotonic shortening against a load corresponding to either 5 or 10 % of a reference force, and average force, stiffness, elastance and resistance over one cycle while the strip length was oscillating sinusoidally by 5 % at 0.2 Hz. For each readout, the logEC50 was calculated and compared. Isotonic shortening with a 5 % load had the lowest logEC50 (-7.13), yielding a greater sensitivity than any other contractile readout (p<0.05). It was followed by isotonic shortening with a 10 % load (-6.66), elastance (-6.46), stiffness (-6.46), resistance (-6.38), isometric force (-6.32), and average force (-6.30). Some of these differences were significant. For example, the EC50 with the average force was 44 % greater than with the elastance (p=0.001). The methacholine sensitivity is thus affected by the contractile readout being measured., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The transitional epithelial cells (urothelium) that line the lumen of the urinary bladder form a barrier between potentially harmful pathogens, toxins, and other bladder contents and the inner layers of the bladder wall. The urothelium, however, is not simply a passive barrier, as it can produce signaling factors, such as ATP, nitric oxide, prostaglandins, and other prostanoids, that can modulate bladder function. We investigated whether substances produced by the urothelium could directly modulate the contractility of the underlying urinary bladder smooth muscle. Force was measured in isolated strips of mouse urinary bladder with the urothelium intact or denuded. Bladder strips developed spontaneous tone and phasic contractions. In urothelium-intact strips, basal tone, as well as the frequency and amplitude of phasic contractions, were 25%, 32%, and 338% higher than in urothelium-denuded strips, respectively. Basal tone and phasic contractility in urothelium-intact bladder strips were abolished by the cyclooxygenase (COX) inhibitor indomethacin (10 µM) or the voltage-dependent Ca 2+ channel blocker diltiazem (50 µM), whereas blocking neuronal sodium channels with tetrodotoxin (1 µM) had no effect. These results suggest that prostanoids produced in the urothelium enhance smooth muscle tone and phasic contractions by activating voltage-dependent Ca 2+ channels in the underlying bladder smooth muscle. We went on to demonstrate that blocking COX inhibits the generation of transient pressure events in isolated pressurized bladders and greatly attenuates the afferent nerve activity during bladder filling, suggesting that urothelial prostanoids may also play a role in sensory nerve signaling. NEW & NOTEWORTHY This paper provides evidence for the role of urothelial-derived prostanoids in maintaining tone in the urinary bladder during bladder filling, not only underscoring the role of the urothelium as more than a barrier but also contributing to active regulation of the urinary bladder. Furthermore, cyclooxygenase products greatly augment sensory nerve activity generated by bladder afferents during bladder filling and thus may play a role in perception of bladder fullness.

Aims: It is well established that intracellular cAMP contributes to the relaxation of vas deferens smooth muscle. In many tissues, intracellular cAMP is actively transported to the extracellular space, where it exerts regulatory functions, via its metabolite adenosine. These actions take place through the cAMP conversion to adenosine by ectoenzymes, a process called "extracellular cAMP-adenosine pathway". Herein, we investigated whether, in addition to ATP, extracellular cAMP might be an alternative source of adenosine, influencing the contraction of vas deferens smooth muscle., Main Methods: The effects of cAMP, 8-Br-cAMP and adenosine were analyzed in the isometric contractions of rat vas deferens. cAMP efflux was analyzed by measuring extracellular cAMP levels after exposure of vas deferens segments to isoproterenol and forskolin in the presence or absence of MK-571, an inhibitor of MRP/ABCC transporters., Key Findings: While 8-Br-cAMP, a cell-permeable cAMP analog, induced relaxation of KCl-precontracted vas deferens, the non-permeant cAMP increased the KCl-induced contractile response, which was mimicked by adenosine, but prevented by inhibitors of ecto-5'-nucleotidase or A 1 receptors. Our results also showed that isoproterenol and forskolin increases cAMP efflux via an MRP/ABCC transporter-dependent mechanism, since it is inhibited by MK-571., Significance: Our data show that activation of β-adrenoceptors and adenylyl cyclase increases cAMP efflux from vas deferens tissue, which modulates the vas deferens contractile response via activation of adenosine A 1 receptors. Assuming that inhibition of vas deferens contractility has been proposed as a strategy for male contraception, the extracellular cAMP-adenosine pathway emerges as a potential pharmacological target that should be considered in studies of male fertility., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In Crohn's Disease (CD), intestinal fibrosis is a prevalent yet unresolved complication arising from chronic and transmural inflammation. The histological assessment of CD intestines shows changes in tissue morphology in all the layers, including the mucosa and muscularis. This study aimed to determine the differences in fibrogenesis between mucosa and muscularis. Human precision-cut intestinal slices (hPCIS) were prepared from human intestine mucosa and muscularis and treated with TGF-β1 and/or PDGF-BB for 72 h. Gene and protein expression and matrix metalloproteinase (MMP) activity were determined. The basal gene expression of various fibrosis markers was higher in muscularis compared to mucosa hPCIS. During incubation, Pro-Collagen-1A1 secretion increased in muscularis but not in mucosa hPCIS. MMP gene expression increased during incubation in mucosa and muscularis hPCIS, except for MMP9, MMP12, and MMP13 in muscularis hPCIS. Incubation with TGF-β1 caused increased COL1A1 expression in the mucosa but not in muscularis hPCIS. In muscularis hPCIS, TGF-β1 treatment caused a decrease in MMP1 and CTSK expression, while MMP13 was increased. In the presence of TGF-β1, protease inhibitor expression was stable, except for SERPINE1, which was increased in muscularis hPCIS. We conclude that fibrogenesis is more pronounced in muscularis hPCIS compared to mucosa hPCIS, especially when stimulated with TGF-β1.

Asthma is a disease characterized by chronic inflammation and hyper responsiveness of airways. We aimed to assess the relaxant potential of phosphodiesterase-4 (PDE4) inhibitors N-sulfonilhidrazonic derivatives on non-asthmatic and asthmatic guinea pig trachea. Firstly, guinea pigs were sensitized and challenged with ovalbumin, and then morphological, and contractile changes were evaluated resulting from asthma, followed by evaluation of relaxant effect of derivatives on guinea pig trachea and the cAMP levels measurement by ELISA. It has been evidenced hypertrophy of airway smooth muscle, inflammatory infiltrate, and vascular abnormalities. Moreover, only sensitized tracheal rings were responsive to OVA. Contractile response to histamine, but not to carbachol, was greater in sensitized animals, however the relaxant response to aminophylline and isoprenaline were the same in non-asthmatics and asthmatics. N-sulfonilhidrazonic derivatives presented equipotent relaxant action independent of epithelium, with exception of LASSBio-1850 that presented a low efficacy (< 50%) and LASSBio-1847 with a 4-fold higher potency on asthmatics. LASSBio-1847 relaxant curve was impaired in the presence of propranolol and potentiated by isoprenaline in both groups. Furthermore, relaxation was potentiated 54- and 4-fold by forskolin in non-asthmatics and asthmatics, respectively. Likewise, LASSBio-1847 potentiated relaxant curve of aminophylline 147- and 4-fold in both groups. The PKA inhibitor H-89 impaired the relaxant potency of the derivative. Finally, LASSBio-1847 increased tracheal intracellular cAMP levels similarly to rolipram, selective PDE4 inhibitor, in both animals. LASSBio-1847 showed to be promising to relax guinea pig trachea from non-sensitized and sensitized guinea pigs by activation of β 2 -adrenergic receptors/AC/cAMP pathway., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We studied the inhibitory actions of docosahexaenoic acid (DHA) on the contractions induced by carbachol (CCh), angiotensin II (Ang II), and bradykinin (BK) in guinea pig (GP) gastric fundus smooth muscle (GFSM), particularly focusing on the possible inhibition of store-operated Ca 2+ channels (SOCCs). DHA significantly suppressed the contractions induced by CCh, Ang II, and BK; the inhibition of BK-induced contractions was the strongest. Although all contractions were greatly dependent on external Ca 2+ , more than 80% of BK-induced contractions remained even in the presence of verapamil, a voltage-dependent Ca 2+ channel inhibitor. BK-induced contractions in the presence of verapamil were not suppressed by LOE-908 (a receptor-operated Ca 2+ channel (ROCC) inhibitor) but were suppressed by SKF-96365 (an SOCC and ROCC inhibitor). BK-induced contractions in the presence of verapamil plus LOE-908 were strongly inhibited by DHA. Furthermore, DHA inhibited GFSM contractions induced by cyclopiazonic acid (CPA) in the presence of verapamil plus LOE-908 and inhibited the intracellular Ca 2+ increase due to Ca 2+ addition in CPA-treated 293T cells. These findings indicate that Ca 2+ influx through SOCCs plays a crucial role in BK-induced contraction in GP GFSM and that this inhibition by DHA is a new mechanism by which this fatty acid inhibits GFSM contractions., (© 2024. The Author(s).)

The Cupressaceae family includes species considered to be medicinal. Their essential oil is used for headaches, colds, cough, and bronchitis. Cedar trees like Chamaecyparis lawsoniana ( C. lawsoniana ) are commonly found in urban areas. We investigated whether C. lawsoniana exerts some of its effects by modifying airway smooth muscle (ASM) contractility. The leaves of C. lawsoniana (363 g) were pulverized mechanically, and extracts were obtained by successive maceration 1:10 ( w : w ) with methanol/CHCl 3 . Guinea pig tracheal rings were contracted with KCl, tetraethylammonium (TEA), histamine (HIS), or carbachol (Cch) in organ baths. In the Cch experiments, tissues were pre-incubated with D-600, an antagonist of L-type voltage-dependent Ca 2+ channels (L-VDCC) before the addition of C. lawsoniana . Interestingly, at different concentrations, C. lawsoniana diminished the tracheal contractions induced by KCl, TEA, HIS, and Cch. In ASM cells, C. lawsoniana significantly diminished L-type Ca 2+ currents. ASM cells stimulated with Cch produced a transient Ca 2+ peak followed by a sustained plateau maintained by L-VDCC and store-operated Ca 2+ channels (SOCC). C. lawsoniana almost abolished this last response. These results show that C. lawsoniana , and its active metabolite quercetin, relax the ASM by inhibiting the L-VDCC and SOCC; further studies must be performed to obtain the complete set of metabolites of the extract and study at length their pharmacological properties.

Ectonucleotidases play an important role in regulating the level of extracellular nucleotides and nucleosides and are an important part of the regulation of the effects of adenosine and ATP on adenosine and P2 receptors, respectively. We have previously established the ambiguous effect of P2 receptor agonists on the contractile activity of smooth muscle tissue in rats with the valproate model of autism. In this work, HPLC was used to evaluate the activity of ectonucleotidases in the smooth muscle tissues of the internal organs of rats with a valproate model of autism. The activity of ectonucleotidases was significantly higher in the smooth muscle tissues of the duodenum, vas deferens, and bladder, but lower in the ileum and uterus. The results obtained make it possible to compare the activity of ectonucleotidases identified here with changes in P2 receptor-mediated contractility of smooth muscle tissues revealed in our previous experiments., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature.)

Airway smooth muscle cell (ASM) is renowned for its involvement in airway hyperresponsiveness through impaired ASM relaxation and bronchoconstriction in asthma, which poses a significant challenge in the field. Recent studies have explored different targets in ASM to alleviate airway hyperresponsiveness, however, a sizeable portion of patients with asthma still experience poor control. In our study, we explored protein phosphatase 2 A (PP2A) in ASM as it has been reported to regulate cellular contractility by controlling intracellular calcium ([Ca 2+ ] i ), ion channels, and respective regulatory proteins. We obtained human ASM cells and lung tissues from healthy and patients with asthma and evaluated PP2A expression using RNA-Seq data, immunofluorescence, and immunoblotting. We further investigated the functional importance of PP2A by determining its role in bronchoconstriction using mouse bronchus and human ASM cell [Ca 2+ ] i regulation. We found robust expression of PP2A isoforms in human ASM cells with PP2Aα being highly expressed. Interestingly, PP2Aα was significantly downregulated in asthmatic tissue and human ASM cells exposed to proinflammatory cytokines. Functionally, FTY720 (PP2A agonist) inhibited acetylcholine- or methacholine-induced bronchial contraction in mouse bronchus and further potentiated isoproterenol-induced bronchial relaxation. Mechanistically, FTY720 inhibited histamine-evoked [Ca 2+ ] i response and myosin light chain (MLC) phosphorylation in the presence of interleukin-13 (IL-13) in human ASM cells. To conclude, we for the first time established PP2A signaling in ASM, which can be further explored to develop novel therapeutics to alleviate airway hyperresponsiveness in asthma. NEW & NOTEWORTHY This novel study deciphered the expression and function of protein phosphatase 2Aα (PP2Aα) in airway smooth muscle (ASM) during asthma and/or inflammation. We showed robust expression of PP2Aα in human ASM while its downregulation in asthmatic ASM. Similarly, we demonstrated reduced PP2Aα expression in ASM exposed to proinflammatory cytokines. PP2Aα activation inhibited bronchoconstriction of isolated mouse bronchi. In addition, we unveiled that PP2Aα activation inhibits the intracellular calcium release and myosin light chain phosphorylation in human ASM.

Parathyroid hormone-related protein (PTHrP) released from detrusor smooth muscle (DSM) cells upon bladder distension attenuates spontaneous phasic contractions (SPCs) in DSM and associated afferent firing to facilitate urine storage. Here, we investigate the mechanisms underlying PTHrP-induced inhibition of SPCs, focusing on large-conductance Ca 2+ -activated K + channels (BK channels) that play a central role in stabilizing DSM excitability. Perforated patch-clamp techniques were applied to DSM cells of the rat bladder dispersed using collagenase. Isometric tension changes were recorded from DSM strips, while intracellular Ca 2+ dynamics were visualized using Cal520 AM -loaded DSM bundles. DSM cells developed spontaneous transient outward potassium currents (STOCs) arising from the opening of BK channels. PTHrP (10 nM) increased the frequency of STOCs without affecting their amplitude at a holding potential of - 30 mV but not - 40 mV. PTHrP enlarged depolarization-induced, BK-mediated outward currents at membrane potentials positive to + 20 mV in a manner sensitive to iberiotoxin (100 nM), the BK channel blocker. The PTHrP-induced increases in BK currents were also prevented by inhibitors of sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA) (CPA 10 µM), L-type voltage-dependent Ca 2+ channel (LVDCC) (nifedipine 3 µM) or adenylyl cyclase (SQ22536 100 µM). PTHrP had no effect on depolarization-induced LVDCC currents. PTHrP suppressed and slowed SPCs in an iberiotoxin (100 nM)-sensitive manner. PTHrP also reduced the number of Ca 2+ spikes during each burst of spontaneous Ca 2+ transients. In conclusion, PTHrP accelerates STOCs discharge presumably by facilitating SR Ca 2+ release which prematurely terminates Ca 2+ transient bursts resulting in the attenuation of SPCs., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The cavernous nerve (CN) is frequently damaged in prostatectomy and diabetic patients with erectile dysfunction (ED), initiating changes in penile morphology including an acute and intense phase of apoptosis in penile smooth muscle and increased collagen, which alter penile architecture and make corpora cavernosa smooth muscle less able to relax in response to neurotransmitters, resulting in ED., Aim: Sonic hedgehog (SHH) is a critical regulator of penile smooth muscle, and SHH treatment suppresses penile remodeling after CN injury through an unknown mechanism; we examine if part of the mechanism of how SHH preserves smooth muscle after CN injury involves bone morphogenetic protein 4 (BMP4) and gremlin1 (GREM1)., Methods: Primary cultures of smooth muscle cells were established from prostatectomy, diabetic, hypertension and Peyronie's (control) (N = 18) patients. Cultures were characterized by ACTA2, CD31, P4HB, and nNOS immunohistochemical analysis. Patient smooth muscle cell growth was quantified in response to BMP4 and GREM1 treatment. Adult Sprague Dawley rats underwent 1 of 3 surgeries: (1) uninjured or CN-injured rats were treated with BMP4, GREM1, or mouse serum albumin (control) proteins via Affi-Gel beads (N = 16) or peptide amphiphile (PA) (N = 26) for 3 and 14 days, and trichrome stain was performed; (2) rats underwent sham (N = 3), CN injury (N = 9), or CN injury and SHH PA treatment for 1, 2, and 4 days (N = 9)., Outcomes: Western analysis for BMP4 and GREM1 was performed; (3) rats were treated with 5E1 SHH inhibitor (N = 6) or IgG (control; N = 6) for 2 and 4 days, and BMP4 and GREM1 localization was examined. Statistics were performed by analysis of variance with Scheffé's post hoc test., Results: BMP4 increased patient smooth muscle cell growth, and GREM1 decreased growth. In rats, BMP4 treatment via Affi-Gel beads and PA increased smooth muscle at 3 and 14 days of treatment. GREM1 treatment caused increased collagen and smooth muscle at 3 days, which switched to primarily collagen at 14 days. CN injury increased BMP4 and GREM1, while SHH PA altered Western band size, suggesting alternative cleavage and range of BMP4 and GREM1 signaling. SHH inhibition in rats increased BMP4 and GREM1 in fibroblasts., Clinical Implications: Understanding how SHH PA preserves and regenerates penile morphology after CN injury will aid development of ED therapies., Strengths and Limitations: SHH treatment alters BMP4 and GREM1 localization and range of signaling, which can affect penile morphology., Conclusion: Part of the mechanism of how SHH regulates corpora cavernosa smooth muscle involves BMP4 and GREM1., (© The Author(s) 2024. Published by Oxford University Press on behalf of The International Society of Sexual Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Numerous studies suggest the involvement of adenosine-5'-triphosphate (ATP) and similar nucleotides in the pathophysiology of asthma. Androgens, such as testosterone (TES), are proposed to alleviate asthma symptoms in young men. ATP and uridine-5'-triphosphate (UTP) relax the airway smooth muscle (ASM) via purinergic P2Y 2 and P2Y 4 receptors and K + channel opening. We previously demonstrated that TES increased the expression of voltage-dependent K + (K V ) channels in ASM. This study investigates how TES may potentiate ASM relaxation induced by ATP and UTP. Tracheal tissues treated with or without TES (control group) from young male guinea pigs were used. In organ baths, tracheas exposed to TES (40 nM for 48 h) showed enhanced ATP- and UTP-evoked relaxation. Tetraethylammonium, a K + channel blocker, annulled this effect. Patch-clamp experiments in tracheal myocytes showed that TES also increased ATP- and UTP-induced K + currents, and this effect was abolished with flutamide (an androgen receptor antagonist). K V channels were involved in this phenomenon, which was demonstrated by inhibition with 4-aminopyridine. RB2 (an antagonist of almost all P2Y receptors except for P2Y 2 ), as well as N-ethylmaleimide and SQ 22,536 (inhibitors of G proteins and adenylyl cyclase, respectively), attenuated the enhancement of the K + currents induced by TES. Immunofluorescence and immunohistochemistry studies revealed that TES did not modify the expression of P2Y 4 receptors or COX-1 and COX-2, while we have demonstrated that this androgen augmented the expression of K V 1.2 and K V 1.5 channels in ASM. Thus, TES leads to the upregulation of P2Y 4 signaling and K V channels in guinea pig ASM, enhancing ATP and UTP relaxation responses, which likely limits the severity of bronchospasm in young males.

Purines such as ATP are regulatory transmitters in motility of the gastrointestinal tract. The aims of this study were to propose functional roles of purinergic regulation of esophageal motility. An isolated segment of the rat esophagus was placed in an organ bath, and mechanical responses were recorded using a force transducer. Exogenous application of ATP (10-100 μM) evoked relaxation of the esophageal smooth muscle in a longitudinal direction under the condition of carbachol (1 μM) -induced precontraction. Pretreatment with a non-selective P2 receptor antagonist, suramin (500 μM), and a P2Y receptor antagonist, cibacron blue F3GA (200 μM), inhibited the ATP (100 μM) -induced relaxation, but a P2X receptor antagonist, pyridoxal phosphate-6-azophenyl-2,4-disulfonic acid (50 μM), did not affect it. A blocker of ATP-dependent potassium channels (K ATP channels), glibenclamide (200 μM), inhibited the ATP-induced relaxation and application of an opener of K ATP channels, nicorandil (50 μM), produced relaxation. The findings suggest that ATP is involved in inhibitory regulation of the longitudinal smooth muscle in the muscularis mucosae of the rat esophagus via activation of P2Y receptors and then opening of K ATP channels., (© 2024. The Author(s).)

Since its first discovery as a bioactive phospholipid inducing potent platelet aggregation, platelet-activating factor (PAF) has been shown to be involved in a wide variety of inflammatory and allergic disease states. Many pharmacological studies in the 1980s and 1990s also showed that PAF induces endothelium-dependent vascular relaxation and contraction of various smooth muscles (SMs), including those in the airway, gastrointestinal organs, and uterus. However, since the late 1990s, there have been few reports on the SM contractions induced by PAF. The lower urinary tract (LUT), particularly the urinary bladder (UB) has attracted recent attention in SM pharmacology research because patients with LUT dysfunctions including overactive bladder are increasing as the population ages. In addition, recent clinical studies have implicated the substantial role of PAF in the inflammatory state in LUT because its production increases with smoking and with cancer. However, the effects of PAF on mechanical activities of LUT SMs including UBSM have not been investigated to date. Recently, we found that PAF very strongly increased mechanical activities of UBSM in guinea pigs and mice, and partly elucidated the possible mechanisms underlying these actions of PAF. In this review, we describe the effects of PAF on LUT SMs by introducing our recent findings obtained in isolated UBSMs and discuss the physiological and pathophysiological significance. We also introduce our data showing the effects of PAF on the SM mechanical activities of genital tissues (prostate and vas deferens).

Functional bowel disorders (FBD) have a major potential to degrade the standards of public life. Juniperus oxycedrus L. (J. oxycedrus) (Cupressaceae) has been described as a plant used in traditional medicine as an antidiarrheal medication. The present study is the first to obtain information on the antispasmodic and antidiarrheic effects of J. oxycedrus aqueous extract through in vitro and in vivo studies. An aqueous extract of J. oxycedrus (AEJO) was extracted by decoctioning air-dried aerial sections of the plant. Antispasmodic activity was tested in an isolated jejunum segment of rats exposed to cumulative doses of drogue extract. The antidiarrheic activity was tested using diarrhea caused by castor oil, a transit study of the small intestine, and castor oil-induced enteropooling assays in mice. In the jejunum of rats, the AEJO (0.1, 0.3 and 1 mg/ml) diminished the maximum tone induced by low K + (25 mM), while it exhibited a weak inhibitory effect on high K + (75 mM) with an IC 50 =0.49 ± 0.01 mg/ml and IC 50 =2.65 ± 0.16 mg/ml, respectively. In the contractions induced by CCh (10 -6 M), AEJO diminished the maximum tone, similar to that induced by low K + (25 mM). with an IC 50 =0.45 ± 0.02 mg/ml. The inhibitory effect of AEJO on low K + induced contractions was significantly diminished in the presence of glibenclamide (GB) (0.3 µM) and 4-aminopyrimidine (4-AP) (100 µM), with IC 50 values of 1.84 ± 0.09 mg/ml. and 1.63 ± 0.16 mg/ml, respectively). The demonstrated inhibitory effect was similar to that produced by a non-competitive antagonist acting on cholinergic receptors and calcium channels. In castor oil-induced diarrhea in mice, AEJO (100, 200, and 400 mg/kg) caused an extension of the latency time, a reduced defecation frequency, and a decrease in the amount of wet feces compared to the untreated group (distilled water). Moreover, it showed a significant anti-motility effect and reduced the amount of fluid accumulated in the intestinal lumen at all tested doses. These findings support the conventional use of Juniperus oxycedrus L. as a remedy for gastrointestinal diseases.

Adrenoceptors importantly contribute to the physiological regulation of lower urinary tract (LUT) function and have become a target of several clinically successful treatments for major LUT diseases. In the bladder dome, β-adrenoceptor subtypes are found in multiple cell types and mediate relaxation of detrusor smooth muscle, perhaps partly indirectly by acting on afferent nerves and cells of the mucosa. β 3 -adrenoceptor agonists such as mirabegron and vibegron are used to treat overactive bladder syndrome. In the bladder trigone and urethra, α 1 -adrenoceptors cause contraction and thereby physiologically contribute to bladder outlet resistance. α 1 -adrenoceptors in the prostate also cause contraction and pathophysiologically elevate bladder outlet resistance leading to voiding dysfunction in benign prostatic hyperplasia. α 1 -adrenoceptor antagonist such as tamsulosin is widely used as a first-line option to treat LUT symptoms in men, but it remains unclear to which extent and how smooth muscle relaxation contributes to symptom relief., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Ethnopharmacological Relevance: Ophiocordyceps sinensis (O. sinensis) is a genus of Ascomycete fungus that is endemic to the alpine meadows of the Tibetan Plateau and adjoining Himalayas. It has been used traditionally as a tonic to improve respiratory health in ancient China as well as to promote vitality and longevity. Bioactive components found in O. sinensis such as adenosine, cordycepin, 3-deoxyadenosine, L-arginine and polysaccharides have gained increasing interest in recent years due to their antioxidative and other properties, which include anti-asthmatic, antiviral, immunomodulation and improvement of general health., Aim of the Study: This study's primary aim was to investigate the effect of a cultivated fruiting body of O. sinensis strain (OCS02®) on airways patency and the secondary focus was to investigate its effect on the lifespan of Caenorhabditis elegans., Materials and Methods: A cultivated strain, OCS02®, was employed and the metabolic profile of its cold-water extract (CWE) was analysed through liquid chromatography-mass spectrometry (LC-MS). Organ bath approach was used to investigate the pharmacological properties of OCS02® CWE when applied on airway tissues obtained from adult male Sprague-Dawley rats. The airway relaxation mechanisms of OCS02® CWE were explored using pharmacological tools, where the key regulators in airway relaxation and constriction were investigated. For the longevity study, age-synchronised, pos-1 RNAi-treated wild-type type Caenorhabditis elegans at the L4 stage were utilised for a lifespan assay., Results: Various glycopeptides and amino acids, particularly a high concentration of L-arginine, were identified from the LC-MS analysis. In airway tissues, OCS02® CWE induced a significantly greater concentration-dependent relaxation when compared to salbutamol. The relaxation response was significantly attenuated in the presence of NG-Nitro-L-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one (ODQ) and several K + channel blockers. The longevity effect induced by OCS02® CWE (5 mg/mL and above) was observed in C. elegans by at least 17%., Conclusions: These findings suggest that the airway relaxation mechanisms of OCS02® CWE involved cGMP-dependent and cGMP-independent nitric oxide signalling pathways. This study provides evidence that the cultivated strain of OCS02® exhibits airway relaxation effects which supports the traditional use of its wild O. sinensis in strengthening respiratory health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Appropriate coordination of smooth muscle contraction and relaxation is essential for normal colonic motility. The impact of perturbed motility ranges from moderate, in conditions such as colitis, to potentially fatal in the case of pseudo-obstruction. The mechanisms underlying aberrant motility and the extent to which they can be targeted pharmacologically are incompletely understood. This study identified colonic smooth muscle as a major site of expression of neuropilin 2 (Nrp2) in mice and humans. Mice with inducible smooth muscle-specific knockout of Nrp2 had an increase in evoked contraction of colonic rings in response to carbachol at 1 and 4 weeks following initiation of deletion. KCl-induced contractions were also increased at 4 weeks. Colonic motility was similarly enhanced, as evidenced by faster bead expulsion in Nrp2-deleted mice versus Nrp2-intact controls. In length-tension analysis of the distal colon, passive tension was similar in Nrp2-deficient and Nrp2-intact mice, but at low strains, active stiffness was greater in Nrp2-deficient animals. Consistent with the findings in conditional Nrp2 mice, Nrp2-null mice showed increased contractility in response to carbachol and KCl. Evaluation of selected proteins implicated in smooth muscle contraction revealed no significant differences in the level of α-smooth muscle actin, myosin light chain, calponin, or RhoA. Together, these findings identify Nrp2 as a novel regulator of colonic contractility that may be targetable in conditions characterized by dysmotility., (Copyright © 2022 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Both chronic obstructive pulmonary disease (COPD) and asthma are severe respiratory diseases. Bitter receptor-mediated bronchodilation is a potential therapy for asthma, but the mechanism underlying the agonistic relaxation of airway smooth muscle (ASM) is not well defined. By exploring the ASM relaxation mechanism of bitter substances, we observed that pretreatment with the bitter substances nearly abolished the methacholine (MCh)-induced increase in the ASM cell (ASMC) calcium concentration, thereby suppressing the calcium-induced contraction release. The ASM relaxation was significantly inhibited by simultaneous deletion of three Gα t proteins, suggesting an interaction between Tas2R and AChR signaling cascades in the relaxation process. Biochemically, the Gα t released by Tas2R activation complexes with AChR and blocks the Gα q cycling of AChR signal transduction. More importantly, a bitter substance, kudinoside A, not only attenuates airway constriction but also significantly inhibits pulmonary inflammation and tissue remodeling in COPD rats, indicating its modulation of additional Gα q -associated pathological processes. Thus, our results suggest that Tas2R activation may be an ideal strategy for halting multiple pathological processes of COPD.

Ethnopharmacological Relevance: Magnolia officinalis Cortex (M. officinalis) is a classical traditional Chinese medicine (TCM) widely used to treat digestive system diseases. It effectively regulates gastrointestinal motility to improve abdominal pain, abdominal distension and other symptoms. Magnolol (MAG) and honokiol (HON) are the main pharmacodynamic components responsible for the gastrointestinal activity of M. officinalis., Aim of the Study: The transient receptor potential (TRP) family is highly expressed in the gastrointestinal tract and participates in the regulation of gastrointestinal motility, visceral hypersensitivity, visceral secretion and other physiological activities. In this study, the calcium-lowering mechanisms of MAG and HON contributing to the smooth muscle relaxation associated with TRP are discussed., Materials and Methods: The relaxation smooth muscle effects of MAG and HON were tested by the isolated intestine tone tests. A synthetic MAG probe (MAG-P) was used to target fishing for their possible target. The distribution of MAG on the smooth muscle was identified by a molecular tracer based on chemical biology. Ca 2+ imaging and dual-luciferase reporter assays were used to determine the effects on the target proteins. Finally, the calcium-mediating effects of MAG and HON on smooth muscle cells and TRPC4-knockdown cells were compared to verify the potential mechanism., Results: After confirming the smooth muscle relaxation in the small intestine induced by MAG and HON, the relaxation effect was identified mainly due to the downregulation of intracellular calcium by controlling external calcium influx. Although MAG and HON inhibited both TRPV4 and TRPC4 channels to reduce calcium levels, the inhibitory effect on TRPC4 channels is an important mechanism of their smooth muscle relaxation effect, since TRPC4 is widely expressed in the small intestinal smooth muscle cells., Conclusions: The inhibition of MAG and HON on TRPC4 channels contributes to the relaxation of intestinal smooth muscle., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Histamine has been implicated in urinary bladder dysfunction as an inflammatory mediator driving sensory nerve hypersensitivity. However, the direct influence of histamine on smooth muscle has not been thoroughly investigated. We hypothesized that histamine directly contracts urinary bladder smooth muscle (UBSM) independent of effects on nerves. Single cell quantitative RT-PCR determined that only histamine H 1 and H 2 receptors were expressed on UBSM cells. In isolated tissue bath experiments, histamine (200 µM) caused a highly variable and rapidly desensitizing contraction that was completely abolished by the H 1 receptor antagonist fexofenadine (5 µM) and the G q/11 inhibitor YM254890 (1 µM). Neither the muscarinic receptor antagonist atropine (1 µM), the Na + channel blocker tetrodotoxin (1 µM), nor the transient receptor potential vanilloid type 1 antagonist capsazepine (10 µM) altered responses to histamine, suggesting that nerve activation was not involved. UBSM desensitization to histamine was not due to receptor internalization, as neither the cholesterol-depleting agent methyl-β-cyclodextrin (10 mM), the dynamin-mediated endocytosis inhibitor dynasore (100 µM), nor the clathrin-mediated endocytosis inhibitor pitstop2 (15 µM) augmented or prolonged histamine contractions. Buffer from desensitized tissues still contracted histamine-naïve tissues, revealing that histamine was not metabolized. Prolonged exposure to histamine also had no effect on contractions due to electrical field stimulation, suggesting that both efferent nerve and UBSM excitability were unchanged. Together, these data suggest that histamine, although able to transiently contract UBSM, does not have a lasting effect on UBSM excitability or responses to efferent nerve input. Thus, any acute effects of histamine directly on UBSM contractility are unlikely to alter urinary bladder function. NEW & NOTEWORTHY Histamine is commonly associated with inflammatory bladder pathologies. We sought to investigate the role of histamine on urinary bladder contractility. Histamine contracts the bladder, but this response is highly variable and desensitizes completely in minutes. This desensitization is not due to internalization of the receptor or metabolism of histamine. Because nerve-evoked contractions are also not increased in the presence of histamine, our findings suggest that histamine is not directly acting to change contractility.

Advanced glycation end products (AGEs) can damage voltage-gated K + (Kv) channels and attenuate coronary artery vasodilation, but the underlying mechanisms remain unclear. The aim of this study was to investigate the role and potential mechanism of PPARγ in AGEs-induced Kv 1 channels impairment. We used both primary rat coronary smooth muscle cells (CSMCs) in vitro and Zucker Diabetic Fatty (ZDF) rat model in vivo. Overexpression of the Pparg gene by lentivirus vector (LV-Pparg) was used to transfect CSMCs for upregulation PPARγ. Kv 1.2 and Kv 1.5 currents were measured by patch clamp. The vascular tone of coronary artery was evaluated by isometric force measurements. The proteins expression of Kv1.2 and Kv1.5 channel were detected by western blot. PPARγ was detected by immunofluorescence and western blot. Oxidative stress markers including superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA) were detected by enzyme linked immunosorbent assay (ELISA). The phosphorylation of p38 mitogen-activated protein kinase (MAPK) and total p38 expression were detected by western blot. The intracellular ROS levels were measured by the fluorescent dye 2',7'- dichlorofluorescein diacetate (DCFDA) and a cellular ROS assay kit. We found that activating PPARγ via LV-Pparg (100 MOI, 5 × 10 8 TU/mL) prevented AGEs (100 μg/mL) -mediated impairment of Kv 1.2 and Kv 1.5 channels activity and improved the reduction of Kv 1.2 and Kv 1.5 protein expression in CSMCs. Isometric force measurements showed that activating PPARγ by pioglitazone (10 mg/kg/d, intragastric administration) improved the impairment of coronary artery vasodilation, and western blot analysis showed that activating PPARγ increased the Kv 1.2 and Kv 1.5 protein expression, while inhibiting PPARγ by GW9662 (10 mg/kg/d, intraperitoneal injection) attenuated these effects in ZDF rats. Furthermore, LV-Pparg overexpression PPARγ attenuated NADPH oxidase activity, which was shown as the reduction of the NOX2 and p22phox expression by western blot analysis, decreased the MDA production and increased the SOD and GPx activities by ELISA, finally led to reduce AGEs-mediated ROS production. Moreover, activating PPARγ by LV-Pparg inhibited AGEs-induced phosphorylation of p38 MAPK, by which could reduce AGEs-mediated NOX2, p22phox expression and ROS production, while CSMCs treatment with SB203580 (10 μmol/L), a p38 MAPK inhibitor, attenuated these effects. Activating PPARγ plays a protective role in AGEs-induced impairment of coronary artery vasodilation by inhibiting p38 phosphorylation to attenuate NOX2 and p22phox expression and further decrease oxidative stress induced by ROS overproduction., (Copyright © 2022 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Rationale: Vascular calcification is a prominent feature of late-stage diabetes, renal and cardiovascular disease (CVD), and has been linked to adverse events. Recent studies in patients reported that plasma levels of osteomodulin (OMD), a proteoglycan involved in bone mineralisation, associate with diabetes and CVD. We hypothesised that OMD could be implicated in these diseases via vascular calcification as a common underlying factor and aimed to investigate its role in this context., Methods and Results: In patients with chronic kidney disease, plasma OMD levels correlated with markers of inflammation and bone turnover, with the protein present in calcified arterial media. Plasma OMD also associated with cardiac calcification and the protein was detected in calcified valve leaflets by immunohistochemistry. In patients with carotid atherosclerosis, circulating OMD was increased in association with plaque calcification as assessed by computed tomography. Transcriptomic and proteomic data showed that OMD was upregulated in atherosclerotic compared to control arteries, particularly in calcified plaques, where OMD expression correlated positively with markers of smooth muscle cells (SMCs), osteoblasts and glycoproteins. Immunostaining confirmed that OMD was abundantly present in calcified plaques, localised to extracellular matrix and regions rich in α-SMA + cells. In vivo, OMD was enriched in SMCs around calcified nodules in aortic media of nephrectomised rats and in plaques from ApoE -/- mice on warfarin. In vitro experiments revealed that OMD mRNA was upregulated in SMCs stimulated with IFNγ, BMP2, TGFβ1, phosphate and β-glycerophosphate, and by administration of recombinant human OMD protein (rhOMD). Mechanistically, addition of rhOMD repressed the calcification process of SMCs treated with phosphate by maintaining their contractile phenotype along with enriched matrix organisation, thereby attenuating SMC osteoblastic transformation. Mechanistically, the role of OMD is exerted likely through its link with SMAD3 and TGFB1 signalling, and interplay with BMP2 in vascular tissues., Conclusion: We report a consistent association of both circulating and tissue OMD levels with cardiovascular calcification, highlighting the potential of OMD as a clinical biomarker. OMD was localised in medial and intimal α-SMA + regions of calcified cardiovascular tissues, induced by pro-inflammatory and pro-osteogenic stimuli, while the presence of OMD in extracellular environment attenuated SMC calcification., (© 2022 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Objectives: This study aimed to identify the effect of trimetazidine (TMZ), an antianginal drug, on detrusor smooth muscle (DSM) contractility and its possible mechanisms of action., Methods: We performed in-vitro contractility studies on isolated mouse DSM strips and investigated the effect of TMZ on Ca2+ levels in fura-2-loaded A7r5 cells., Key Findings: TMZ (300 or 1000 µM) inhibited carbachol (CCh)- and KCl-induced contractions and produced a concentration-dependent (10-1000 µM) relaxation in KCl-precontracted DSM strips. TMZ-induced relaxation was markedly decreased by BaCl2, an inward-rectifying K+ channel blocker, but was not altered by preincubation with tetraethylammonium, glibenclamide, 4-aminopyridine, propranolol, L-NAME or methylene blue. TMZ (300 or 1000 µM) reduced both the CaCl2-induced contraction of depolarized DSM strips under Ca2+-free conditions and the CCh-induced contraction of DSM strips preincubated with nifedipine in Ca2+-containing Krebs solution. Furthermore, TMZ (1000 µM) significantly decreased the Ca2+ levels in fura-2-loaded A7r5 cells., Conclusions: TMZ decreased DSM contractility and caused a concentration-dependent relaxation of the tissue possibly through its actions on Ca2+ transients and K+ channels. Our results provide preclinical evidence that TMZ would be a potential candidate to treat disorders related to the overactivity of the bladder., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

We investigated the potential inhibitory effects of docosahexaenoic acid (DHA) on the contractions of guinea pig tracheal smooth muscles in response to U46619 (a thromboxane A 2 (TXA 2 ) mimetic) and prostaglandin F 2α (PGF 2α ) to examine whether this n-3 polyunsaturated fatty acid suppresses prostanoid-induced tracheal contractions. DHA (3 × 10 -5  M) significantly suppressed tracheal contractions elicited by lower concentrations of U46619 (10 -8  M) and PGF 2α (5 × 10 -7  M) (vs. control), although it did not suppress the contractions induced by higher concentrations (U46619: 10 -7  M; PGF 2α : 10 -5  M). Supporting these findings, DHA (4 × 10 -5  M/6 × 10 -5  M) shifted the concentration-response curves for U46619 (10 -9 -10 -6  M) and PGF 2α (10 -8 -10 -5  M) to the right. However, the slope of the regression line in the Schild plot of DHA vs. U46619/PGF 2α was larger than unity. The tracheal contractions induced by U46619 (10 -8  M) and PGF 2α (5 × 10 -7  M) were significantly suppressed by the prostanoid TP receptor antagonist SQ 29,548 (10 -6  M) (vs. ethanol-treated). In contrast, DHA (4 × 10 -5  M) did not show significant inhibitory effects on the contractions induced by acetylcholine (10 -8 -10 -4  M), histamine (10 -8 -10 -4  M), and leukotriene D 4 (10 -11 -10 -7  M) (vs. ethanol-treated). These findings indicate that DHA selectively suppresses tracheal contractions induced by U46619 and PGF 2α . Therefore, DHA may be a useful therapeutic agent against asthma associated with tracheal/bronchial hyper-constriction caused by prostanoids including TXA 2 and PGF 2α .

The proinflammatory cytokine tumor necrosis factor-α (TNF-α) augments intracellular Ca 2+ signaling and contractile responses of airway smooth muscles, leading to airway hyperresponsiveness. However, the underlying mechanism has not been fully elucidated. This study aimed to investigate the cellular mechanism of the potentiated contraction of mouse tracheal smooth muscle induced by TNF-α. The results showed that TNF-α triggered facilitation of mouse tracheal smooth muscle contraction in an epithelium-independent manner. The TNF-α-induced hypercontractility could be suppressed by the protein kinase C inhibitor GF109203X, the tyrosine kinase inhibitor genistein, the Src inhibitor PP2, or the L-type voltage-dependent Ca 2+ channel blocker nifedipine. Following TNF-α incubation, the α 1C L-type Ca 2+ channel (Ca V 1.2) was up-regulated in cultured primary mouse tracheal smooth muscle cells. Pronounced phosphotyrosine levels were observed in mouse tracheas. In conclusion, this study shows that TNF-α enhanced airway smooth muscle contraction via protein kinase C-Src-Ca V 1.2 pathways, which provides novel insights into the pathologic role of proinflammatory cytokines in mediating airway hyperresponsiveness., (Copyright © 2022 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Aims: We examined the potential stimulatory effects of U46619 (a prostanoid TP receptor agonist) and five prostanoids on the contractile activities of urinary bladder smooth muscle (UBSM), focusing on the role of the TP receptor and its associated Ca 2+ influx routes to understand the roles of prostanoids in the regulation of UB contractile activity., Main Methods: Changes in the basal tone and spontaneous contractile activity (amplitude and frequency) of isolated guinea pig UBSM were measured isotonically. The presence of TP receptors in UBSM was examined by RT-qPCR and immunofluorescence., Key Findings: U46619, prostaglandin (PG) E 2 , PGF 2α , and PGA 2 enhanced UBSM basal tone and spontaneous contractile activities, which were measured as amplitudes and frequencies. The enhancing effects of U46619 were completely suppressed by SQ 29,548 (a TP receptor antagonist), which also partially suppressed the stimulating effects of other prostanoids. The expression of TP receptors in UBSMs was verified at the mRNA and protein level. The enhancing effects of U46619 completely disappeared in Ca 2+ -free solution. U46619-enhanced basal tone was completely suppressed by verapamil, an inhibitor of voltage-dependent Ca 2+ channels (VDCCs), and verapamil strongly decreased the spontaneous contraction frequency. The spontaneous contractions remaining in the presence of verapamil were strongly suppressed by SKF-96365 (an inhibitor of receptor-operated Ca 2+ channels (ROCCs)/store-operated Ca 2+ channels (SOCCs)), but not by LOE-908 (an inhibitor of ROCCs)., Significance: Prostanoids can enhance UBSM contractile activities and thus may be endogenous candidates for induction of detrusor overactivity. The TP receptor and TP-receptor-activated VDCCs/SOCCs are key molecules responsible for these effects., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Acrolein is a metabolite of cyclophosphamide (CYP), an alkylating agent used for a wide range of benign and malignant diseases. CYP treatments are known to trigger hemorrhagic cystitis in patients and animals. Significant effort has been made to prevent CYP/acrolein-induced cystitis, while still maintaining its therapeutic benefits. As a result, supplementary therapeutic options to mediate the protective role against CYP/acrolein and lower doses of CYP are currently given to targeted patients, as compared to past treatments. There is still a need to further study the effects of the repeated low-dose CYP/acrolein on the pathophysiology of the urinary bladder. In our study, a one-time treatment of acrolein and repeated low-dose acrolein triggered the thickening of the smooth muscle and lamina propria in the urinary bladder of C57BL/6J mice, respectively. The first dose of acrolein did not trigger voiding dysfunction, but the second dose triggered high-volume low-frequency voiding. Interestingly, our new scoring criteria and concurrent behavioral assessment revealed that mice with repeated low-dose acrolein had a wider opening of eyes in response to mechanical stimuli. Our study suggests that clinical symptoms among patients undergoing prolonged low-dose CYP may differ from previously reported symptoms of CYP-induced hemorrhagic cystitis.

G protein-coupled receptors display multifunctional signaling, offering the potential for agonist structures to promote conformational selectivity for biased outputs. For β 2 -adrenergic receptors (β 2 AR), unbiased agonists stabilize conformation(s) that evoke coupling to Gαs (cyclic adenosine monophosphate [cAMP] production/human airway smooth muscle [HASM] cell relaxation) and β-arrestin engagement, the latter acting to quench Gαs signaling, contributing to receptor desensitization/tachyphylaxis. We screened a 40-million-compound scaffold ranking library, revealing unanticipated agonists with dihydroimidazolyl-butyl-cyclic urea scaffolds. The S -stereoisomer of compound C1 shows no detectable β-arrestin engagement/signaling by four methods. However, C1- S retained Gαs signaling-a divergence of the outputs favorable for treating asthma. Functional studies with two models confirmed the biasing: β 2 AR-mediated cAMP signaling underwent desensitization to the unbiased agonist albuterol but not to C1- S , and desensitization of HASM cell relaxation was observed with albuterol but not with C1- S These HASM results indicate biologically pertinent biasing of C1- S , in the context of the relevant physiologic response, in the human cell type of interest. Thus, C1- S was apparently strongly biased away from β - arrestin, in contrast to albuterol and C5- S C1- S structural modeling and simulations revealed binding differences compared with unbiased epinephrine at transmembrane (TM) segments 3,5,6,7 and ECL2. C1- S (R2 = cyclohexane) was repositioned in the pocket such that it lost a TM6 interaction and gained a TM7 interaction compared with the analogous unbiased C5- S (R2 = benzene group), which appears to contribute to C1- S biasing away from β-arrestin. Thus, an agnostic large chemical-space library identified agonists with receptor interactions that resulted in relevant signal splitting of β 2 AR actions favorable for treating obstructive lung disease., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

Here we investigate mechanisms underlying spontaneous phasic contractions (SPCs) and sympathetic control of contractility in the rat epididymis, a long tubular duct involved in transportation and maturation of sperm. Longitudinal contractions of short segments (~ 1.5 mm) of rat proximal and distal caudal epididymal duct were measured + / - nerve stimulation. The extent of sympathetic innervation of these duct regions was determined by immunohistochemistry. Proximal caudal duct segments (150-300 μm dia.) exhibited SPCs, while distal segments (350-500 μm) were quiescent in ~ 80% of preparations. SPC amplitude and frequency were reduced by the L-type voltage-dependent Ca 2+ channel (LVDCC) blocker nifedipine (1 μM), with the T-type voltage-dependent Ca 2+ channel (TVDCC) blocker ML218 (1 μM) specifically decreasing SPC frequency. SPCs were inhibited upon blockade of the SR/ER Ca 2+ -ATPase (CPA 10 μM). SPCs were also inhibited by caffeine (1 μM), 2-APB (100 μM), niflumic acid (100 μM), or by lowering extracellular [Cl - ] from 134.4 to 12.4 mM but not by ryanodine (25 μM) or tetracaine (100 μM). Electrical field stimulation (EFS) at 2 Hz for 60 s caused a sustained α 1 -adrenoceptor-sensitive contraction in distal segments and enhanced and/or induced α 2 -adrenoceptor-sensitive oscillatory phasic contractions in proximal and distal segments, the latter mimicked by application of the α 2 -adrenoceptor agonist clonidine. We hypothesise that SPCs in the proximal cauda are triggered by pacemaker mechanisms involving rhythmic IP 3 receptor-operated SR/ER store Ca 2+ release and resultant activation of CaCC with TVDCCs and possibly LVDCCs subserving in this process. Sympathetic nerve-released noradrenaline induces α 2 -adrenoceptor-mediated phasic contractions in the proximal and distal cauda. These findings provide new pharmacological targets for male infertility and contraception., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pupil diameter fluctuates in association with changes in brain states induced by the neuromodulator systems. However, it remains unclear how the neuromodulator systems control the activity of the iris sphincter (constrictor) and dilator muscles to change the pupil size. The present study compared temporal patterns of pupil dilation during movement when each muscle was pharmacologically manipulated in the human eye. When the iris sphincter muscle was blocked with tropicamide, the latency of pupil dilation was delayed and the magnitude of pupil dilation was reduced during movement. In contrast, when the iris dilator muscle was continuously stimulated with phenylephrine, the latency and magnitude of rapid pupil dilation did not differ from the untreated control eye, but sustained pupil dilation was reduced until the end of movement. These results suggest that the iris sphincter muscle, which is under the control of the parasympathetic pathway, is quickly modulated by the neuromodulator system and plays a major role in rapid pupil dilation. However, the iris dilator muscle receives signals from the neuromodulator system with a slow latency and is involved in maintaining sustained pupil dilation. NEW & NOTEWORTHY By pharmacologically manipulating the pupil dilator and constrictor muscles of human eye separately, we found that the pupil constrictor muscle is a primary controller of rapid pupil dilation upon brain arousal. However, the pupil dilator muscle, which is innervated by the sympathetic nervous system and is generally considered as a major regulator of pupil dilation, is not involved in rapid pupil dilation, but was involved in long-lasting pupil dilation.

Context: Cucumber ( Cucumis sativus Linn. [Cucurbitaceae]) is widely known for its purgative, antidiabetic, antioxidant, and anticancer therapeutic potential. However, its effect on gastrointestinal (GI) disease is unrecognised., Objective: This study investigated the effect of C. sativus fruit extract (CCE) on intestinal chloride secretion, motility, and motor function, and the role of TMEM16A chloride channels., Materials and Methods: CCE extracts were obtained from commercially available cucumber. Active fractions were then purified by HPLC and analysed by high resolution mass spectrometry. The effect of CCE on intestinal chloride secretion was investigated in human colonic T84 cells, ex vivo mouse intestinal tissue using an Ussing chamber, and the two-electrode voltage-clamp technique to record calcium sensitive TMEM16A chloride currents in Xenopus laevis oocytes. In vivo , intestinal motility was investigated using the loperamide-induced C57BL/6 constipation mouse model. Ex vivo contractility of mouse colonic smooth muscles was assessed by isometric force measurements., Results: CCE increased the short-circuit current (ΔIsc 34.47 ± µA/cm 2 ) and apical membrane chloride conductance (ΔI Cl 95 ± 8.1 µA/cm 2 ) in intestinal epithelial cells. The effect was dose-dependent, with an EC 50 value of 0.06 µg/mL. CCE stimulated the endogenous TMEM16A-induced Cl - current in Xenopus laevis oocytes. Moreover, CCE increased the contractility of smooth muscle in mouse colonic tissue and enhanced small bowel transit in CCE treated mice compared to loperamide controls. Mass spectrometry suggested a cucurbitacin-like analogue with a mass of 512.07 g/mol underlying the bioactivity of CCE., Conclusion: A cucurbitacin-like analog present in CCE activates TMEM16A channels, which may have therapeutic potential in cystic fibrosis and intestinal hypodynamic disorders.