Search

Background: Carbon nanoparticles (CNPs) have been reported to boost plant growth, while the mechanism that CNPs enhanced potassium uptake for plant growth has not been reported so far. Results: In this study, the function that CNPs promoted potassium uptake in BY-2 cells was established and the potassium accumulated in cells had a significant correlation with the fresh biomass of BY-2 cells. The K+ accumulation in cells increased with the increasing concentration of CNPs. The K+ influx reached high level after treatment with CNPs and was significantly higher than that of the control group and the negative group treated with K+ channels blocker, tetraethylammonium chloride (TEA+). The K+ accumulation was not reduced in the presence of CNPs inhibitors. In the presence of potassium channel blocker TEA+ or CNPs inhibitors, the NKT1 gene expression was changed compared with the control group. The CNPs were found to preferentially transport K+ than other cations determined by rectification of ion current assay (RIC) in a conical nanocapillary. Conclusions: These results indicated that CNPs upregulated potassium gene expression to enhance K+ accumulation in BY-2 cells. Moreover, it was speculated that the CNPs simulated protein of ion channels via bulk of carboxyl for K+ permeating. These findings will provide support for improving plant growth by carbon nanoparticles. [ABSTRACT FROM AUTHOR]

Background: Recent studies described a critical role for microglia in Parkinson's disease (PD), where these central nerve system resident immune cells participate in the neuroinflammatory microenvironment that contributes to dopaminergic neurons loss in the substantia nigra. Understanding the phenotype switch of microgliosis in PD could help to identify the molecular mechanism which could attenuate or delay the progressive decline in motor function. KCa3.1 has been reported to regulate the "pro-inflammatory" phenotype switch of microglia in neurodegenerative pathological conditions.Methods: We here investigated the effects of gene deletion or pharmacological blockade of KCa3.1 activity in wild-type or KCa3.1-/- mice after treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a mouse model of PD. MPTP-induced PD mouse model was subjected to the rotarod test to evaluate the locomotor ability. Glia activation and neuron loss were measured by immunostaining. Fluo-4 AM was used to measure cytosolic Ca2+ level in 1-methyl-4-phenylpyridinium (MPP+)-induced microgliosis in vitro.Results: We report that treatment of MPTP-induced PD mouse model with gene deletion or pharmacological blockade of KCa3.1 with senicapoc improves the locomotor ability and the tyrosine hydroxylase (TH)-positive neuron number and attenuates the microgliosis and neuroinflammation in the substantia nigra pars compacta (SNpc). KCa3.1 involves in store-operated Ca2+ entry-induced Ca2+ overload and endoplasmic reticulum stress via the protein kinase B (AKT) signaling pathway during microgliosis. Gene deletion or blockade of KCa3.1 restored AKT/mammalian target of rapamycin (mTOR) signaling both in vivo and in vitro.Conclusions: Taken together, these results demonstrate a key role for KCa3.1 in driving a pro-inflammatory microglia phenotype in PD. [ABSTRACT FROM AUTHOR]

ShK is a 35-residue disulfide-linked polypeptide produced by the sea anemone Stichodactyla helianthus, which blocks the potassium channels Kv1.1 and Kv1.3 with pM affinity. An analogue of ShK has been developed that blocks Kv1.3 > 100 times more potently than Kv1.1, and has completed Phase 1b clinical trials for the treatment of autoimmune diseases such as psoriasis and rheumatoid arthritis. Previous studies have indicated that ShK undergoes a conformational exchange that is critical to its function, but this has proved difficult to characterise. Here, we have used high hydrostatic pressure as a tool to increase the population of the alternative state, which is likely to resemble the active form that binds to the Kv1.3 channel. By following changes in chemical shift with pressure, we have derived the chemical shift values of the low- and high-pressure states, and thus characterised the locations of structural changes. The main difference is in the conformation of the Cys17-Cys32 disulfide, which is likely to affect the positions of the critical Lys22-Tyr23 pair by twisting the 21–24 helix and increasing the solvent exposure of the Lys22 sidechain, as indicated by molecular dynamics simulations. [ABSTRACT FROM AUTHOR]

There is significant interest in the potential utility of small-molecule activator compounds to mitigate cardiac arrhythmia caused by loss of function of hERG1a voltage-gated potassium channels. Zebrafish (Danio rerio) have been proposed as a cost-effective, high-throughput drug-screening model to identify compounds that cause hERG1a dysfunction. However, there are no reports on the effects of hERG1a activator compounds in zebrafish and consequently on the utility of the model to screen for potential gain-of-function therapeutics. Here, we examined the effects of hERG1a blocker and types 1 and 2 activator compounds on isolated zkcnh6a (zERG3) channels in the Xenopus oocyte expression system as well as action potentials recorded from ex vivo adult zebrafish whole hearts using optical mapping. Our functional data from isolated zkcnh6a channels show that under the conditions tested, these channels are blocked by hERG1a channel blockers (dofetilide and terfenadine), and activated by type 1 (RPR260243) and type 2 (NS1643, PD-118057) hERG1a activators with higher affinity than hKCNH2a channels (except NS1643), with differences accounted for by different biophysical properties in the two channels. In ex vivo zebrafish whole hearts, two of the three hERG1a activators examined caused abbreviation of the action potential duration (APD), whereas hERG1a blockers caused APD prolongation. These data represent, to our knowledge, the first pharmacological characterization of isolated zkcnh6a channels and the first assessment of hERG enhancing therapeutics in zebrafish. Our findings lead us to suggest that the zebrafish ex vivo whole heart model serves as a valuable tool in the screening of hKCNH2a blocker and activator compounds. [ABSTRACT FROM AUTHOR]

Breast cancer is the most frequent tumor in women. The recent advent of cyclin-dependent kinase (CDK) 4/6 inhibitors palbociclib and ribociclib has represented a major step forward for patients with hormone receptor-positive breast cancer. These two agents have showed similar efficacy in terms of breast cancer outcome but different cardiotoxic effects. In particular, ribociclib, but not palbociclib, has been associated with QT interval prolongation, and the mechanisms underlying this event are still unclear. In order to clarify such difference, we matched the candidate genes associated with QT interval prolongation with genes whose expression is altered following palbociclib or ribociclib treatment. We also investigated whether pharmacokinetic and pharmacodynamic characteristics, such as IC50 (hERG) [concentration of drug producing 50% inhibition (human ether-à-go-go related gene)] and maximum concentration (Cmax), could justify the different effects on QT interval prolongation. Our results show that ribociclib, but not palbociclib, could act by down-regulating the expression of KCNH2 (encoding for potassium channel hERG) and up-regulating SCN5A and SNTA1 (encoding for sodium channels Nav1.5 and syntrophin-α1, respectively), three genes associated with long QT syndrome. Consistent with the cardiotoxicity induced by ribociclib, its IC50 (hERG)/free concentration (Cmax free) ratio is closer to the safety threshold than that of palbociclib. In summary, we hypothesize that the different cardiotoxicity associated with ribociclib and palbociclib could be due to the alteration of potassium and sodium channels induced by ribociclib. A better comprehension of the mechanisms of cardiac channelopathies and drug-induced QT interval prolongation will be fundamental to avoid serious and potentially lethal adverse events and, as a consequence, optimize the management of breast cancer patients. [ABSTRACT FROM AUTHOR]

Previous studies suggested that pu-erh tea aqueous extract could lower blood pressure and ameliorate hypertension symptoms. However, the antihypertension mechanisms of pu-erh tea remain unclear. In this work, the direct effects of pu-erh tea on vessels and cells were investigated by detecting isometric tension and intracellular calcium ([Ca2+]i), respectively. Additionally, to identify the main active components, the aqueous extract of pu-erh was separated by organic solvents to obtain various fractions, and the effects of these fractions on arteries were assessed. The results showed that pu-erh aqueous extract vasodilated rat thoracic aortas preconstricted by phenylephrine or KCl. These vasodilation effects were not significantly affected by the removal of the endothelium or by preincubation with potassium channel blockers (tetraethylammonium, glibenclamide, aminopyridine, or barium chloride). Moreover, pu-erh aqueous extract could reduce the vessel contractibility induced by CaCl2 and phenylephrine under KCl-depolarizing or Ca2+-free buffer conditions, respectively. Furthermore, pu-erh aqueous extract attenuated the KCl-induced increase in [Ca2+]i in cultured rat aortic smooth muscle A7r5 cells. In addition, the chloroform precipitate of pu-erh aqueous extract produced the most potent vasodilation. Theabrownins (the characteristic components of pu-erh tea) accounted for 41.91 ± 1.09 % of the chloroform precipitate and vasodilated arteries in an endothelium-independent manner. In addition, the vasodilation effect of caffeine was verified. In conclusion, theabrownins and caffeine should be the two main active components in pu-erh tea. Pu-erh aqueous extract vasodilated arteries in an endothelium-independent manner, which might partly be attributed to the decrease in extracellular Ca2+ influx. Moreover, our study provided data on the potential mechanism of the hypotensive actions of pu-erh tea, which might improve our understanding of the effect of pu-erh tea on the prevention and treatment of hypertension. [ABSTRACT FROM AUTHOR]

Opioid-induced respiratory depression (OIRD) is the major cause of death associated with opioid analgesics and drugs of abuse, but the underlying cellular and molecular mechanisms remain poorly understood. We investigated opioid action in vivo in unanesthetized mice and in in vitro medullary slices containing the preBötzinger Complex (preBötC), a locus critical for breathing and inspiratory rhythm generation. Although hypothesized as a primary mechanism, we found that mu-opioid receptor (MOR1)-mediated GIRK activation contributed only modestly to OIRD. Instead, mEPSC recordings from genetically identified Dbx1- derived interneurons, essential for rhythmogenesis, revealed a prevalent presynaptic mode of action for OIRD. Consistent with MOR1-mediated suppression of presynaptic release as a major component of OIRD, Cacna1a KO slices lacking P/Q-type Ca2+ channels enhanced OIRD. Furthermore, OIRD was mimicked and reversed by KCNQ potassium channel activators and blockers, respectively. In vivo whole-body plethysmography combined with systemic delivery of GIRK- and KCNQ-specific potassium channel drugs largely recapitulated these in vitro results, and revealed state-dependent modulation of OIRD. We propose that respiratory failure from OIRD results from a general reduction of synaptic efficacy, leading to a state-dependent collapse of rhythmic network activity. [ABSTRACT FROM AUTHOR]

Background. Delayed rectifier K+-channel, Kv1.3, is most predominantly expressed in T-lymphocytes and macrophages. In such leukocytes, Kv1.3-channels play pivotal roles in the activation and proliferation of cells, promoting cellular immunity. Since leukocyte-derived cytokines stimulate fibroblasts to produce collagen fibers in inflamed kidneys, Kv1.3-channels expressed in leukocytes would contribute to the progression of tubulointerstitial renal fibrosis. Methods. Male Sprague-Dawley rats that underwent unilateral ureteral obstruction (UUO) were used at 1, 2, or 3 weeks after the operation. We examined the histological features of the kidneys and the leukocyte expression of Kv1.3-channels. We also examined the therapeutic effects of a selective channel inhibitor, margatoxin, on the progression of renal fibrosis and the proliferation of leukocytes within the cortical interstitium. Results. In rat kidneys with UUO, progression of renal fibrosis and the infiltration of leukocytes became most prominent at 3 weeks after the operation, when Kv1.3-channels were overexpressed in proliferating leukocytes. In the cortical interstitium of margatoxin-treated UUO rat kidneys, immunohistochemistry revealed reduced expression of fibrosis markers. Additionally, margatoxin significantly decreased the numbers of leukocytes and suppressed their proliferation. Conclusions. This study clearly demonstrated that the numbers of T-lymphocytes and macrophages were markedly increased in UUO rat kidneys with longer postobstructive days. The overexpression of Kv1.3-channels in leukocytes was thought to be responsible for the proliferation of these cells and the progression of renal fibrosis. This study strongly suggested the therapeutic usefulness of targeting lymphocyte Kv1.3-channels in the treatment of renal fibrosis. [ABSTRACT FROM AUTHOR]

Background: Prolonged-release (PR) fampridine is a potassium channel blocker used as a symptomatic treatment for walking disability in patients with multiple sclerosis (MS). Its clinical effects in such patients have not been systematically reviewed, and may be more wide-ranging than expected.Objectives: To summarize the evidence on the effects of PR fampridine in patients with MS.Methods: A systematic search of Pubmed, Scopus (including EMBASE), and PsycINFO (completed in 01/2019) was carried out to identify randomized controlled trials (RCT) that compared PR fampridine to placebo. When appropriate, data were pooled using a random-effects model, and standardized mean differences (SMD) were computed. Study quality was assessed using the Downs and Black checklist. PRISMA guidelines were followed. All retrieved functional outcomes were categorized according to the International Classification of Functioning, Disability and Health (ICF).Results: A total of 706 articles were screened for inclusion. Twenty RCTs involving 2616 patients met the eligibility criteria. Most studies were of good-to-excellent quality. PR fampridine administration resulted in significant benefits in relation to walking short distances (SMD: 1.23 (95% IC 0.65-1.81)) and perceived walking capacity (0.64 (0.27-1.02)). Its effects on muscle strength and middle-distance walking were not significant (0.53 (- 0.04 to 1.10) and 0.31 (- 0.18 to 0.80), respectively). No effect on higher-level cognitive functions (- 0.07 (- 0.58 to 0.45)) or hand and arm use (0.16 (- 0.33 to 0.64)) was observed. Individual studies reported effects on other outcomes across the ICF domains.Conclusions: There is strong evidence that PR fampridine exerts strong effects on the ability to walk short distances and on perceived walking capacity. Other effects of PR fampridine according to the ICF are possible but still unclear. [ABSTRACT FROM AUTHOR]

Background and Aim: Simaba ferruginea A.St.-Hil. Popularly known as "calunga," is a typical Brazilian cerrado plant whose rhizomes are popular for treating diarrhea.Aims: The aim of this study was to evaluate the spasmolytic activity and the antidiarrheal effect of the ethanolic extract obtained from S. ferruginea (Sf-EtOH).Methods: Ileal segments (1-2 cm) from male Wistar rats were mounted in isolated organ baths and connected to a force transducer, and then to an amplifier which was connected to a computer (AVS Projetos/São Paulo-SP). After stabilization for 60 min, under tension (1 gf), two submaximal contractions were induced with KCl 40 mM or carbachol 10-6 M on ileal segments. During the third tonic and sustained contraction, Sf-EtOH was added in cumulative concentrations to the organ bath. Incubations with L-NAME (10-4 M), ODQ (10-5 M), TEA+ (5 or 1 mM), glibenclamide (10-5 M), or apamine (100 nM) were prepared (n = 5), separately and used to verify the involvement of the nitric oxide synthase, guanylate cyclase, and potassium channels in the relaxing effect. The results were expressed as mean ± standard error of the mean and were statistically evaluated using one-way ANOVA followed by Bonferroni test, when necessary *p < 0.05.Results: Sf-EtOH promotes relaxation on rat isolated ileum pre-contracted with CCh and KCl in a concentration-dependent manner. Sf-EtOH also inhibited ileum contractions against cumulative concentrations of carbachol (CCh), KCl, and CaCl2, shifting the curves to the right in a non-parallel manner with an Emax reduction. In the presence of potassium channel blockers, Sf-EtOH shifted the curves to the right with a reduction of Emax, suggesting the involvement of BKCa, KATP, and SKCa in its spasmolytic effect. In the presence of L-NAME or ODQ, the relaxation curves were shifted to the right, suggesting the involvement of this pathway in Sf-EtOH spasmolytic effect.Conclusions: Sf-EtOH acts in a concentration-dependent manner, involving the positive modulation of K+ channels and NO pathway. [ABSTRACT FROM AUTHOR]

Photopharmacology relies on ligands that change their pharmacodynamics upon photoisomerization. Many of these ligands are azobenzenes that are thermodynamically more stable in their elongated trans‐configuration. Often, they are biologically active in this form and lose activity upon irradiation and photoisomerization to their cis‐isomer. Recently, cyclic azobenzenes, so‐called diazocines, have emerged, which are thermodynamically more stable in their bent cis‐form. Incorporation of these switches into a variety of photopharmaceuticals could convert dark‐active ligands into dark‐inactive ligands, which is preferred in most biological applications. This "pharmacological sign‐inversion" is demonstrated for a photochromic blocker of voltage‐gated potassium channels, termed CAL, and a photochromic opener of G protein‐coupled inwardly rectifying potassium (GIRK) channels, termed CLOGO. [ABSTRACT FROM AUTHOR]

KCNT1 encodes a sodium-activated potassium channel highly expressed in the brain, regulating hyperpolarization following repetitive firing. Mutations in KCNT1 were originally implicated in autosomal-dominant nocturnal frontal lobe epilepsy and epilepsy of infancy with migrating focal seizures. It is now known that there is variability in phenotypic expression and incomplete penetrance. We describe 2 patients with KCNT1 -related epilepsy, one with epilepsy of infancy with migrating focal seizures and one with multifocal epilepsy. As most patients with KCNT1 variants have treatment-resistant epilepsy, drugs that specifically target the KCNT1 channel have been of great interest. Quinidine, a broad-spectrum potassium channel blocker, has shown promise; however, clinical trial results have been variable. Our patient with epilepsy of infancy with migrating focal seizures did not respond to a trial of quinidine at 6 weeks of age—one of the earliest reported quinidine trials in the literature for KCNT1 -related epilepsy. This indicates that timing of treatment and response may not be related. Both patients responded to high-dose phenobarbital. The patient with epilepsy of infancy with migrating focal seizures also had a significant reduction in seizures with potassium bromide (KBr). Our data suggest that alternative therapies to quinidine should be considered as a therapeutic option for patients with KCNT1 -related epilepsy. Although improved seizure control led to parent-reported improvements in neurodevelopment, it is unknown if phenobarbital and KBr impact the overall developmental trajectory of patients with KCNT1 -related epilepsy. Further multicenter longitudinal studies are required. [ABSTRACT FROM AUTHOR]

Introduction: The upstroke of optical action potentials (APs) recorded from intact hearts are generally recognized to be slower than those recorded with microelectrodes. This is thought to reflect spatial signal averaging within the volume of tissue that makes up the optical signal. However, to date, there has been no direct experimental study on the relationship between conduction velocity (CV) and optical AP upstroke morphology in the intact heart. Notably, it is known that sodium channel block and gap junction inhibition, which both slow CV, exert differential effects on the upstroke velocity of microelectrode-recorded APs. Whether such differences are evident in optical APs is not known. The present study sought to determine the relationship between tissue CV and optical AP upstroke velocity in intact mouse hearts. Materials and Methods: Isolated, perfused mouse hearts were stained with the potentiometric dye Rh-237. Fluorescent signals were recorded from across the anterior surface of the left and right ventricles during constant pacing. Maximum rate of change in fluorescence (dF/dtmax) and tissue CV were assessed in control conditions, during an acute period of low-flow ischemia, and following perfusion of flecainide (1–3 μmol/L), a sodium channel blocker, or carbenoxolone (10–50 μmol/L), a gap junction inhibitor. Results: During epicardial pacing, an anisotropic pattern was observed in both activation and dF/dtmax maps, with more rapid optical AP upstroke velocities orientated along the fastest conduction paths (and vice versa). Low-flow ischemia resulted in a time-dependent slowing of ventricular CV, which was accompanied by a concomitant reduction in optical AP upstroke velocity. All values returned to baseline on tissue reperfusion. Both flecainide and carbenoxolone were associated with a concentration-dependent reduction in CV and decrease in optical AP upstroke velocity, despite distinct mechanisms of action. Similar responses to carbenoxolone were observed for low- (156 μm pixel with) and high- (20 μm pixel width) magnification recordings. Comparison of data from all interventions revealed a linear relationship between CV and upstroke dF/dt. Conclusion: In intact mouse hearts, slowing of optical AP upstroke velocity is directly proportional to the change in CV associated with low-flow ischemia, sodium channel block, and gap junction inhibition. [ABSTRACT FROM AUTHOR]

The gastroprotective potential of the methanolic extracts from peels (MEPe), seeds (MESe) and pulp (MEPu) of Chrysophyllum cainito L. (Sapotaceae) fruits was evaluated in mice using ethanol/HCl- and indomethacin-induced ulcer, as well as the antiulcer effect of the juice and flour from this fruit. The lowest oral gastroprotective dose of MEPe, MESe and MEPu against ethanol/HCl was 3, 3 and 10 mg/kg, respectively. Moreover, all extracts increased mucin secretion at 176, 198 and 193%. Intraperitoneal administration of MEPe (0.3 mg/kg), MESe (0.3 mg/kg) and MEPu (1 mg/kg) also promoted gastroprotection against ethanol/HCl. In addition, MEPe (3 mg/kg, p.o), MESe (3 mg/kg, p.o) and MEPu (10 mg/kg, p.o) reduced indomethacin-induced gastric ulcer in mice by 78, 70 and 50%, respectively. Regarding the mode of action, the gastroprotective effect of MEPe was decreased by the pre-administration of N-ethylmaleimide (NEM, a sulfhydryl group chelator, 10 mg/kg, i.p), glibenclamide (a potassium channel blocker, 10 mg/kg, i.p), yohimbine (10 mg/kg, i.p, an alpha-adrenergic receptor antagonist, 10 mg/kg, i.p) and indomethacin (a cyclooxygenase inhibitor, 10 mg/kg, i.p). The gastroprotective effect of MESe was reduced by the pre-administration of NEM, glibenclamide, N-Nitro-l-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor, 70 mg/kg, i.p) and yohimbine, while MEPu had the gastroprotective effect decreased in animals pretreated with NEM and L-NAME. However, the extracts did not reduce gastric acid secretion. The supplementation with the flour from C. cainito fruit at 10% by 7 days, but not the juice intake, displayed gastroprotective potential, evidencing the fruit as a promising functional food. Together, the antiulcer effect of extracts of the C. cainito fruit in different experimental models was confirmed by the favoring of mucosal protective mechanisms among different, but complementary, modes of action. In parallel, the gastroprotective effects of the flour from C. cainito fruit were also described. [ABSTRACT FROM AUTHOR]

We examined mechanisms of ammonia handling in the anterior, mid, and posterior intestine of unfed and fed freshwater rainbow trout (Oncorhynchus mykiss), with a focus on the Na+:K+:2Cl− co-transporter (NKCC), Na+:K +-ATPase (NKA), and K+ channels. NKCC was localized by immunohistochemistry to the mucosal (apical) surface of enterocytes, and NKCC mRNA was upregulated after feeding in the anterior and posterior segments. NH4+ was equally potent to K+ in supporting NKA activity in all intestinal sections. In vitro gut sac preparations were employed to examine mucosal ammonia flux rates (Jmamm, disappearance from the mucosal saline), serosal ammonia flux rates (Jsamm, appearance in the serosal saline), and total tissue ammonia production rates (Jtamm = Jsamm − Jmamm). Bumetanide (10−4 mol L−1), a blocker of NKCC, inhibited Jsamm in most preparations, but this was largely due to reduction of Jtamm; Jmamm was significantly inhibited only in the anterior intestine of fed animals. Ouabain (10−4 mol L−1), a blocker of NKA, generally reduced both Jmamm and Jsamm without effects on Jtamm in most preparations, though the anterior intestine was resistant after feeding. Barium (10−2 mol L−1), a blocker of K+ channels, inhibited Jmamm in most preparations, and Jsamm in some, without effects on Jtamm. These pharmacological results, together with responses to manipulations of serosal and mucosal Na+ and K+ concentrations, suggest that NKCC is not as important in ammonia absorption as previously believed. NH4+ appears to be taken up through barium-sensitive K+ channels on the mucosal surface. Mucosal NH4+ uptake via both NKCC and K+ channels is energized by basolateral NKA, which plays an additional role in scavenging NH4+ on the serosal surface to possibly minimize blood toxicity or enhance ion uptake and amino acid synthesis following feeding. Together with recent findings from other studies, we have provided an updated model to describe the current understanding of intestinal ammonia transport in teleost fish. [ABSTRACT FROM AUTHOR]

Context: Avanafil is a smooth muscle relaxant that is clinically used to treat erectile dysfunction. It is an inhibitor of phosphodiesterase-5 (PDE5), the enzyme that catalyzes the metabolism of cyclic guanosine monophosphate (cGMP). The inhibitory effect of avanafil on isolated detrusor muscle contractility has not been studied. Aims: This study investigated the inhibitory effect of avanafil on isolated caprine (goat) detrusor muscle contractility and the possible mechanisms involved. Settings and Design: 80 mM potassium chloride (KCl)-induced contractility of the isolated goat detrusor was studied using a physiograph. Materials and Methods: Ten caprine detrusor strips were made to contract using 80 mM KCl before and after addition of three concentrations (10, 30, and 60 μM) of avanafil. Three reversal agents, ODQ, a guanylyl cyclase inhibitor; glibenclamide, an adenosine triphosphate (ATP)-sensitive potassium channel blocker; and iberiotoxin, a calcium-sensitive potassium (BKCa) channel blocker, were investigated for their ability to reverse the inhibitory effect of 30 μM avanafil on KCl-induced detrusor contractility. Statistical Analysis Used: The nonparametric statistical test, Kruskal–Wallis test, was used for the analysis of the data. Results: Avanafil caused a statistically significant inhibition of detrusor contractility at 30 and 60 μM concentrations. The inhibitory effect of 30 μM avanafil on detrusor contractility was significantly reversed by the addition of ODQ, glibenclamide, and iberiotoxin. Conclusions: Avanafil inhibits the contractility of the isolated detrusor by inhibiting PDE5, leading to raised cellular levels of cGMP. The raised levels of cGMP could have inhibited detrusor contractility by activating cGMP-dependent protein kinase, by opening ATP-sensitive potassium channels, and by opening BKCa. Avanafil could be evaluated for treating clinical conditions requiring relaxation of the detrusor like overactive bladder. [ABSTRACT FROM AUTHOR]

Background: ATP‐sensitive potassium (KATP) channel opener levcromakalim induces migraine attacks in migraine patients. Underlying mechanisms responsible for headache and migraine induction after levcromakalim infusion are unknown. Objective: To investigate the effect of levcromakalim on the cranial arteries and to explore the possible relationship between the middle meningeal artery (MMA) dilation and headache. Methods: In a double‐blind, randomized, placebo‐controlled study, 20 healthy volunteers were scanned at the baseline and repeatedly after infusion of levcromakalim (n = 14) and placebo (n = 6). All participants received a subcutaneous injection of sumatriptan 6 mg before the last scanning. Results: The MMA circumference was significantly larger after levcromakalim compared with placebo (P < .0001). The MMA dilation lasted over 5 hours during observational period. We found a significant association between headache and MMA dilation (P < .0001). The superficial temporal artery (STA) circumference was significantly larger after levcromakalim compared with placebo (P = .03) over the initial period (110 minutes). Over the entire observational period, there was no difference in circumference of the STA and the middle cerebral artery (MCA) between levcromakalim and placebo. Conclusion: Levcromakalim dilated the MMA but not MCA. The MMA dilation was associated with headache. Future studies should investigate whether opening of KATP channels can activate and sensitize the perivascular nociceptors. [ABSTRACT FROM AUTHOR]

Keywords: TASK-1; KCNK3; pulmonary hypertension; atrial fibrillation; A293 EN TASK-1 KCNK3 pulmonary hypertension atrial fibrillation A293 N.PAG N.PAG 3 04/26/21 20210412 NES 210412 Introduction The authors report in a porcine model of persistent atrial fibrillation (AF) that long term I in vivo i pharmacological inhibition of TASK-1 potassium channels with A293 compound (1 mg/kg/day) has antiarrhythmic effects, suggesting that TASK-1 inhibition can be used to counteract rhythm abnormalities in AF patients (Wiedmann et al., [24]). Importantly, in contrast to other cell types, TASK-1 was the unique TASK channel expressed in the pulmonary vasculature (Olschewski et al., [20]) making pulmonary vascular cells more susceptible to TASK-1 channel inhibition than other tissues. Pharmacologic TWIK-related acid-sensitive K+ channel (TASK-1) potassium channel inhibitor A293 facilitates acute cardioversion of paroxysmal atrial fibrillation in a porcine large animal model. [Extracted from the article]

Objectives: To elucidate the mechanism of action of the α1‐blocker, naftopidil, in partial bladder outlet obstruction animals, by studying non‐voiding contractions, and the levels of mediators were measured with resiniferatoxin treatment. Methods: A total of 35 female Wistar rats were randomly divided into a sham or bladder outlet obstruction group, and rats in each group were given vehicle or resiniferatoxin. Incomplete urethral ligation was applied to the bladder outlet obstruction group. After cystometry, the intravesical level of prostaglandin E2 and adenosine 5′‐triphosphate was measured in the instilled perfusate collected. Naftopidil was given at the time of cystometry. Results: In bladder outlet obstruction rats, non‐voiding contractions, bladder capacity, and the intravesical levels of prostaglandin E2 and adenosine 5′‐triphosphate were markedly increased compared with sham rats. Naftopidil decreased non‐voiding contractions, enlarged the bladder capacity, and decreased the intravesical levels of prostaglandin E2 and adenosine 5′‐triphosphate. Resiniferatoxin enhanced non‐voiding contractions. The effects of naftopidil on non‐voiding contractions and the intravesical level of prostaglandin E2, but not adenosine 5′‐triphosphate, were tolerant to resiniferatoxin. Conclusions: In bladder outlet obstruction rats, one cause of generation of non‐voiding contractions might be bladder wall distension, but not transient receptor potential cation channel V1. The increase in intravesical prostaglandin E2 might also be associated with the generation of non‐voiding contractions. Naftopidil inhibits the increase in non‐voiding contractions and decreases the intravesical level of prostaglandin E2, which are independent of transient receptor potential cation channel V1. [ABSTRACT FROM AUTHOR]

Introduction: There are no validated, practical, and quantitative measures of disease severity in Lambert-Eaton myasthenia (LEM).Methods: Data from the Effectiveness of 3,4-Diaminopyridine in Lambert-Eaton Myasthenic Syndrome (DAPPER) trial were analyzed to assess triple timed up-and-go (3TUG) reproducibility and relationships between 3TUG times and other measures of LEM severity.Results: The coverage probability technique showed ≥0.90 probability for an acceptable 3TUG difference of ≤0.2, indicating that it is reproducible in LEM patients. The correlation between 3TUG times and lower extremity function scores was significant in subjects who continued and in those who were withdrawn from 3,4-diaminopyridine free base. Worsening patient-reported Weakness Self-Assessment Scale and Investigator Assessment of Treatment Effect scores corresponded with prolongation of 3TUG times.Discussion: The 3TUG is reproducible, demonstrates construct validity for assessment of lower extremity function in LEM patients, and correlates with changes in patient and physician assessments. These findings, along with prior reliability studies, indicate 3TUG is a valid measure of disease severity in LEM. [ABSTRACT FROM AUTHOR]

Background: Although ClC-2 channels are important in colonic Cl- secretion, it is unclear about their roles in small intestinal anion secretion. Therefore, we sought to examine whether ClC-2 channels play important roles in anion secretion, particularly duodenal bicarbonate secretion (DBS).Methods: Duodenal mucosae from mice were stripped of seromuscular layers and mounted in Ussing chambers. Both duodenal short-circuit current (Isc) and HCO3- secretion in vitro were simultaneously recorded. DBS in vivo was measured by a CO2-sensitive electrode.Results: Lubiprostone, a selective ClC-2 activator, concentration-dependently increased both duodenal Isc and DBS only when applied basolaterally, but not when applied apically. Removal of extracellular Cl- abolished lubiprostone-induced duodenal Isc, but did not alter HCO3- secretion even in the presence of DIDS, a Cl-/HCO3- exchanger inhibitor. However, further addition of glibenclamide, a CFTR channel blocker, abolished lubiprostone-evoked HCO3- secretion. Moreover, lubiprostone-induced HCO3- secretion was impaired in CFTR-/- mice compared to wild-type littermates. Luminal perfusion of duodenal lumen with lubiprostone did not alter basal DBS in vivo, but lubiprostone (i.p.) was able to induce DBS, which was also significantly inhibited by Cd2+, a ClC-2 channel blocker. [Ca2+]cyt level, Ca2+-activated K+ channel- and cAMP-mediated duodenal Isc, and HCO3- secretion were unchanged by lubiprostone.Conclusions: We have provided the first evidence for the novel functional role of basolateral ClC-2 channels in the regulation of duodenal anion secretion. [ABSTRACT FROM AUTHOR]

Methanolic extract of Clinacanthus nutans Lindau leaves (MECN) has been reported to exert antinociceptive activity. The present study aimed to elucidate the possible antinociceptive mechanisms of a lipid-soluble fraction of MECN, which was obtained after sequential extraction in petroleum ether. The petroleum ether fraction of C. nutans (PECN), administered orally to mice, was (i) subjected to capsaicin-, glutamate-, phorbol 12-myristate 13-acetate-, bradykinin-induced nociception model; (ii) prechallenged (intraperitoneal (i.p.)) with 0.15 mg/kg yohimbine, 1 mg/kg pindolol, 3 mg/kg caffeine, 0.2 mg/kg haloperidol, or 10 mg/kg atropine, which were the respective antagonist of α2-adrenergic, β-adrenergic, adenosinergic, dopaminergic, or muscarinic receptors; and (iii) prechallenged (i.p.) with 10 mg/kg glibenclamide, 0.04 mg/kg apamin, 0.02 mg/kg charybdotoxin, or 4 mg/kg tetraethylammonium chloride, which were the respective inhibitor of ATP sensitive-, small conductance Ca2+-activated-, large conductance Ca2+-activated-, or nonselective voltage-activated-K+ channel. Results obtained demonstrated that PECN (100, 250, and 500 mg/kg) significantly (P<0.05) inhibited all models of nociception described earlier. The antinociceptive activity of 500 mg/kg PECN was significantly (P<0.05) attenuated when prechallenged with all antagonists or K+ channel blockers. However, only pretreatment with apamin and charybdotoxin caused full inhibition of PECN-induced antinociception. The rest of the K+ channel blockers and all antagonists caused only partial inhibition of PECN antinociception, respectively. Analyses on PECN's phytoconstituents revealed the presence of antinociceptive-bearing bioactive compounds of volatile (i.e., derivatives of γ–tocopherol, α–tocopherol, and lupeol) and nonvolatile (i.e., cinnamic acid) nature. In conclusion, PECN exerts a non-opioid-mediated antinociceptive activity involving mainly activation of adenosinergic and cholinergic receptors or small- and large-conductance Ca2+-activated-K+ channels. [ABSTRACT FROM AUTHOR]

Summary: Male gamete chemotaxis towards the female gamete is a general strategy to facilitate the sexual reproduction in many marine eukaryotes. Biochemical studies of chemoattractants for male gametes of brown algae have advanced in the 1970s and 1980s, but the molecular mechanism of male gamete responses to the attractants remains elusive. In sea urchin, a K+ channel called the tetraKCNG channel plays a fundamental role in sperm chemotaxis and inhibition of K+ efflux through this channel by high K+ seawater blocks almost all cell responses to the chemoattractant. This signalling mechanism could be conserved in marine invertebrates as tetraKCNG channels are conserved in the marine invertebrates that exhibit sperm chemotaxis. We confirmed that high K+ seawater also inhibited sperm chemotaxis in ascidian, Ciona intestinalis (robusta), in this study. Conversely, the male gamete chemotaxis towards the female gamete of a brown alga, Mutimo cylindricus , was preserved even in high K+ seawater. This result indicates that none of the K+ channels is essential for male gamete chemotaxis in the brown alga, suggesting that the signalling mechanism for chemotaxis in this brown alga is quite different from that of marine invertebrates. Correlated to this result, we revealed that the channels previously proposed as homologues of tetraKCNG in brown algae have a distinct domain composition from that of the tetraKCNG. Namely, one of them possesses two repeats of the six transmembrane segments (diKCNG) instead of four. The structural analysis suggests that diKCNG is a cyclic nucleotide-modulated and/or voltage-gated K+ channel. [ABSTRACT FROM AUTHOR]

Introduction: We recently demonstrated the beneficial effects of 4-aminopyridine (4-AP), a potassium channel blocker, in enhancing remyelination and recovery of nerve conduction velocity and motor function after sciatic nerve crush injury in mice. Although muscle atrophy occurs very rapidly after nerve injury, the effect of 4-AP on muscle atrophy and intrinsic muscle contractile function is largely unknown.Methods: Mice were assigned to sciatic nerve crush injury and no-injury groups and were followed for 3, 7, and 14 days with/without 4-AP or saline treatment. Morphological, functional, and transcriptional properties of skeletal muscle were assessed.Results: In addition to improving in vivo function, 4-AP significantly reduced muscle atrophy with increased muscle fiber diameter and contractile force. Reduced muscle atrophy was associated with attenuated expression of atrophy-related genes and increased expression of proliferating stem cells.Discussion: These findings provide new insights into the potential therapeutic benefits of 4-AP against nerve injury-induced muscle atrophy and dysfunction. Muscle Nerve 60: 192-201, 2019. [ABSTRACT FROM AUTHOR]

Ginkgo biloba extracts (EGb) alleviate myocardial ischemia/reperfusion (MI/R) injury. However, the underlying mechanisms have not yet been characterized. This study aimed to investigate whether activation of large-conductance Ca 2 + -activated K + channels at the inner mitochondrial membrane ( mitoBK Ca ) of cardiomyocytes is involved in Ginkgo biloba extract-mediated cardioprotection. Shuxuening injection (SXNI, 12.5 ml/kg/d), a widely prescribed herbal medicine containing Ginkgo biloba extracts in China, or vehicle, was administered to C57BL/6 mice via tail vein injection for one week prior to surgical procedures. The mitoBKCa blocker paxilline (PAX) (1 ml/kg, 115 nM) was administered via tail vein injection 30 min prior to the onset of ischemia. The mice were randomly divided into the following groups: Sham, MI/R, MI/R+SXNI, and MI/R+SXNI+PAX. MI/R was induced by ligating the left anterior descending coronary artery for 30 min with subsequent reperfusion for 24 h. SXNI pretreatment conferred cardioprotective effects against MI/R injury as evidenced by reduced infarct size, improved cardiac function, and improved mitochondrial function. However, these effects were abrogated by co-administration with PAX. In addition, activation of mitoBKCa by Ginkgo biloba extract EGb761 reduced hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury in vitro through the inhibition of mitochondrial fragmentation, restoration of the mitochondrial membrane potential, decreased generation of superoxide, and inhibition of apoptosis which is associated with alleviating mitochondrial Ca 2 + overload. These results indicated that Ginkgo biloba extracts pretreatment protected against MI/R injury via activation of mitoBKCa. [ABSTRACT FROM AUTHOR]

Key points: Activation of axonal dopamine D2 receptors (D2Rs) increases action potential (AP) threshold, and thus decreases neuronal excitability in layer II stellate cells of medial entorhinal cortex.Endogenous dopamine release increases the AP threshold of stellate cells by activating D2Rs.Activation of D2Rs shifts the activation curve of T‐type Ca2+ channels in a positive direction in a protein kinase A‐dependent manner.Immunofluorescence staining reveals the presence of T‐type Ca2+ channels and D2Rs in the axon initial segments (AISs).This research makes the pioneering discovery of D2R‐induced AP threshold plasticity in AISs of stellate cells. The findings are likely to have significant implications for understanding the cellular processes by which dopamine influences neuronal intrinsic excitability. Stellate cells in the medial entorhinal cortex (MEC) are considered to constitute the largest population of grid cells, which provide spatial representation to support animal estimation of location. Although dopaminergic fibres from the ventral tegmental area and substantia nigra pars compacta innervate the majority of the cortex, including the MEC, little is known about how dopamine modulates the function of MEC stellate cells. Because dopamine D2 receptors (D2Rs) are involved in spatial cognition and MEC contains high levels of D2Rs, we investigated how D2R activation modulates the neuronal intrinsic excitability of stellate cells. Electrophysiological recordings, optogenetics and molecular biology experiments were performed to investigate the mechanism in mice. Activation of axonal D2Rs, not dendritic or somatic D2Rs, elevated the action potential (AP) threshold and decreased the intrinsic excitability of stellate cells, which was caused by shifting rightward the activation properties of T‐type Ca2+ channels in a D2R–protein kinase A‐dependent manner without affecting their steady‐state inactivation curve. In support, immunofluorescence assays revealed colocalization of D2Rs and Cav3.2 calcium channels within the axon initial segment. These findings are likely to have significant implications for understanding the cellular processes by which dopamine influences neuronal excitability and they may also be applicable to other hippocampal and cortical regions as dopaminergic fibres innervate wide brain regions. Taken together, these findings provide a novel cellular mechanism by which D2Rs modulate AP threshold of stellate cells through T‐type Ca2+ channels in MEC, indicating that D2Rs of MEC play a vital role in modulating the information processing of stellate cells. Key points: Activation of axonal dopamine D2 receptors (D2Rs) increases action potential (AP) threshold, and thus decreases neuronal excitability in layer II stellate cells of medial entorhinal cortex.Endogenous dopamine release increases the AP threshold of stellate cells by activating D2Rs.Activation of D2Rs shifts the activation curve of T‐type Ca2+ channels in a positive direction in a protein kinase A‐dependent manner.Immunofluorescence staining reveals the presence of T‐type Ca2+ channels and D2Rs in the axon initial segments (AISs).This research makes the pioneering discovery of D2R‐induced AP threshold plasticity in AISs of stellate cells. The findings are likely to have significant implications for understanding the cellular processes by which dopamine influences neuronal intrinsic excitability. [ABSTRACT FROM AUTHOR]

Background: This study was undertaken to explore the role of total flavones of Camellia (TFC) on the cerebrovascular dysfunction in rats after experimental subarachnoid hemorrhage (SAH). Materials and Methods: The contraction and dilation of cerebral basilar artery (BA), nitric oxide (NO) level, and nitric oxide synthase (NOS) activity in rat serum and the expression of endothelial NOS (eNOS) in cerebral vessels were measured. Furthermore, the effect of potassium channel blockers, endothelium removal, L-NG-nitroarginine methyl ester (L-NAME), or prostacyclin I2 (PG I2) production inhibitor on the response of isolated BA derived from normal rats was also evaluated to explore the underlying mechanism of vasodilation induced by total flavones. Results: The contraction of rat BA to U46619 markedly increased and the vasodilation to acetylcholine remarkably reduced after SAH. Interestingly, these vascular dysfunctions were profoundly ameliorated by pretreatment of TFC. Moreover, total flavones could induce a concentration-dependent relaxation in isolated BA from normal rats, which was obviously eliminated by co-application of potassium channel blockers, ChTx and Apamin, application of L-NAME, or endothelial removal. In addition, total flavones pretreatment obviously improved the expression of eNOS in BA, serum NO level, and NOS activity at 48 h after SAH. Conclusion: These findings revealed that TFC has protective effect on cerebrovascular dysfunction after SAH and demonstrated that the protection could be due to its upregulation of eNOS expression and activation of potassium channel. [ABSTRACT FROM AUTHOR]

Fragile X syndrome (FXS) is characterized by hypersensitivity to sensory stimuli, including environmental sounds. We compared the auditory brainstem response (ABR) recorded in vivo in mice lacking the gene (Fmr1-/y) for fragile X mental retardation protein (FMRP) with that in wild-type animals. We found that ABR wave I, which represents input from the auditory nerve, is reduced in Fmr1-/y animals, but only at high sound levels. In contrast, wave IV, which represents the activity of auditory brainstem nuclei is enhanced at all sound levels, suggesting that loss of FMRP alters the central processing of auditory signals. Current-clamp recordings of neurons in the medial nucleus of the trapezoid body in the auditory brainstem revealed that, in contrast to neurons from wild-type animals, sustained depolarization triggers repetitive firing rather than a single action potential. In voltage-clamp recordings, K+ currents that activate at positive potentials ("high-threshold" K+ currents), which are required for high-frequency firing and are carried primarily by Kv3.1 channels, are elevated in Fmr1-/y mice, while K+ currents that activate near the resting potential and inhibit repetitive firing are reduced. We therefore tested the effects of AUT2 [((4-({5-[(4R)-4-ethyl-2,5-dioxo-1-imidazolidinyl]-2-pyridinyl}oxy)-2-(1-methylethyl) benzonitrile], a compound that modulates Kv3.1 channels. AUT2 reduced the high-threshold K+ current and increased the low-threshold K+ currents in neurons from Fmr1-/y animals by shifting the activation of the high-threshold current to more negative potentials. This reduced the firing rate and, in vivo, restored wave IV of the ABR. Our results from animals of both sexes suggest that the modulation of the Kv3.1 channel may have potential for the treatment of sensory hypersensitivity in patients with FXS. [ABSTRACT FROM AUTHOR]

Venoms from marine animals have been recognized as a new emerging source of peptide-based therapeutics. Several peptide toxins from sea anemone have been investigated as therapeutic leads or pharmacological tools. Venom complexity should be further highlighted using combined strategies of large-scale sequencing and data analysis which integrated transcriptomics and proteomics to elucidate new proteins or peptides to be compared among species. In this work, transcriptomic and proteomic analyses were combined to identify six groups of expressed peptide toxins in Zoanthus natalensis. These include neurotoxin, hemostatic and hemorrhagic toxin, protease inhibitor, mixed function enzymes, venom auxiliary proteins, allergen peptides, and peptides related to the innate immunity. Molecular docking analysis indicated that one expressed Zoanthus Kunitz-like peptide, ZoaKuz1, could be a voltage-gated potassium channels blocker and, hence, it was selected for functional studies. Functional bioassays revealed that ZoaKuz1 has an intrinsic neuroprotective activity in zebrafish model of Parkinson's disease. Since pharmacological blockade of KV channels is known to induce neuroprotective effects, ZoaKuz1 holds the potential to be developed in a therapeutic tool to control neural dysfunction by slowing or even halting neurodegeneration mediated by ion-channel hyperactivity. [ABSTRACT FROM AUTHOR]

Scutellaria baicalensis (S. baicalensis) has been used to manage diarrhea, and its anti-inflammatory effects are responsible for anti-diarrheal effects. However, there are no data concerning its direct effect on colonic motility. Therefore, the effects of the major components of S. baicalensis (baicalin, baicalein and wogonin) on colonic motility were investigated. A segment of the distal colon of rats was placed in Krebs solution to monitor spontaneous giant contractions (GCs). Changes in GCs were recorded after applying baicalin, baicalein or wogonin. After pretreatment with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), 1H-(1,2,4)-oxadiazolo (4,2-a) quinoxalin-1-one (ODQ), tetradotoxin, w-conotoxin, apamin, and iberiotoxin, changes in GCs by wogonin were recorded and analyzed. The segment of the distal colon showed spontaneous GCs at a mean amplitude of 3.7±0.3 g with a frequency of 0.8±0.1/min. Baicalin, baicalein, and wogonin reduced both the amplitude and the frequency of GCs in a dose-dependent manner. Wogonin had the most potent inhibitory effect on GCs (IC50 was 14.6 µM in amplitude and 14.2 µM in frequency). Wogonin-induced GC reduction was not significantly affected by the inhibition of nitric oxide/cGMP pathways with L-NAME and ODQ. Blocking the enteric neurotransmission with tetradotoxin and ω-conotoxin was ineffective on the wogonin-induced reduction of GCs. Ca2+-activated K+ (KCa) channel blockers (apamin and iberiotoxin) significantly attenuated the inhibitory effects of wogonin on GCs (P<0.01). Wogonin was effective in inhibiting colonic motility, probably through the opening of KCa channels located in the smooth muscle apparatus. These findings suggest that wogonin may be a candidate drug for the management of dysmotility-related diarrhea. [ABSTRACT FROM AUTHOR]

Renal vasoconstriction, an early manifestation of ischemic acute kidney injury (AKI), results in renal hypoperfusion and a rapid decline in kidney function. The pathophysiological mechanisms that underlie ischemia-reperfusion (IR)-induced renal insufficiency are poorly understood, but possibilities include alterations in ion channel-dependent renal vasoregulation. In the present study, we show that pharmacological activation of TRPV4 channels constricted preglomerular microvessels and elicited renal hypoperfusion in neonatal pigs. Bilateral renal ischemia followed by short-term reperfusion increased TRPV4 protein expression in resistance size renal vessels and TRPV4-dependent cation currents in renal vascular smooth muscle cells (SMCs). Selective TRPV4 channel blockers attenuated IR-induced reduction in total renal blood flow (RBF), cortical perfusion, and glomerular filtration rate (GFR). TRPV4 inhibition also diminished renal IR-induced increase in AKI biomarkers. Furthermore, the level of angiotensin II (Ang II) was higher in the urine of IR- compared with sham-operated neonatal pigs. IR did not alter renal vascular expression of Ang II type 1 (AT1) receptors. However, losartan, a selective AT1 receptor antagonist, ameliorated IR-induced renal insufficiency in the pigs. Blockade of TRPV4 channels attenuated Ang II-evoked receptor-operated Ca2+ entry and constriction in preglomerular microvessels. TRPV4 inhibition also blunted Ang II-induced increase in renal vascular resistance (RVR) and hypoperfusion in the pigs. Together, our data suggest that SMC TRPV4-mediated renal vasoconstriction and the ensuing increase in RVR contribute to early hypoperfusion and renal insufficiency elicited by renal IR in neonatal pigs. We propose that multimodal signaling by renal vascular SMC TRPV4 channels controls neonatal renal microcirculation in health and disease. [ABSTRACT FROM AUTHOR]

Flavonoids belong to a large group of polyphenolic compounds that are widely present in plants. Certain flavonoids, including naringenin, have cytoprotective properties. Although the antioxidant effect has long been thought to be a crucial factor accounting for the cellular effects of flavonoids, mitochondrial channels have emerged recently as targets for cytoprotective strategies. In the present study, we characterized interactions between naringenin and the mitochondrial potassium (mitoBKCa and mitoKATP) channels recently described in dermal fibroblasts. With the use of the patch‐clamp technique and mitoplasts isolated from primary human dermal fibroblast cells, our study shows that naringenin in micromolar concentrations leads to an increase in mitoBKCa channel activity. The opening probability of the channel decreased from 0.97 in the control conditions (200 μmol/L Ca2+) to 0.06 at a low Ca2+ level (1 μmol/L) and increased to 0.85 after the application of 10 μmol/L naringenin. Additionally, the activity of the mitoKATP channel increased following the application of 10 μmol/L naringenin. To investigate the effects of naringenin on mitochondrial function, the oxygen consumption of dermal fibroblast cells was measured in potassium‐containing media. The addition of naringenin significantly and dose‐dependently increased the respiratory rate from 5.8 ± 0.2 to 14.0 ± 0.6 nmol O2 × min−1 × mg protein−1. Additionally, a Raman spectroscopy analysis of skin penetration indicated that the naringenin was distributed in all skin layers, including the epidermis and dermis. In this study, we demonstrated that a flavonoid, naringenin, can activate two potassium channels present in the inner mitochondrial membrane of dermal fibroblasts. [ABSTRACT FROM AUTHOR]

Background: Memantine is one of the important clinical medications in treating moderate to severe Alzheimer disease. The effect of memantine on preventing or treating punctate allodynia has been thoroughly studied but not on the induction of dynamic allodynia. The aim of this study is to investigate whether memantine could prevent the induction of dynamic allodynia and its underlying spinal mechanisms. Results: (1) In in vivo spared nerve injury pain model, pretreatment with memantine at a lower dose (10 nmol, intrathecal; memantine-10) selectively prevented the induction of dynamic allodynia but not the punctate allodynia. (2) Pretreatment with either MK801-10 (MK801-10 nmol, intrathecal) or higher dose of memantine (30 nmol, intrathecal; memantine-30) prevented the induction of both dynamic and punctate allodynia. (3) Memantine-10 showed significant effect on the inhibition of the spared nerve injury-induced overactivation of microglia in spinal dorsal horn. (4) In contrast, in complete freund0s adjuvant (CFA) model, memantine-10 neither affected the CFA injection-induced activation of microglia in spinal dorsal horn nor the induction of dynamic allodynia. (5) Immunohistological studies showed Kir2.1 channel distributed widely and colocalized with microglia in the spinal dorsal horn of mice. (6) Pretreatment with either minocycline, a microglia inhibitor, or ML133, a Kir2.1 inhibitor, both selectively prevented the overactivation of microglia in spinal dorsal horn and the induction of dynamic allodynia following spared nerve injury. Conclusion: The selective inhibitory effect on the induction of dynamic allodynia in spared nerve injury model by low dose of the memantine (memantine-10) was tightly correlated with the blockade of microglia Kir2.1 channel to suppress the microglia activation. [ABSTRACT FROM AUTHOR]

GluA2-lacking Ca2+-permeable AMPARs (CP-AMPARs) play integral roles in synaptic plasticity and can mediate excitotoxic cellular signaling at glutamatergic synapses. However, the developmental profile of functional CP-AMPARs at the auditory brainstem remains poorly understood. Through a combination of electrophysiological and live-cell Ca2+ imaging from mice of either sex, we show that the synaptic release of glutamate from the calyx of Held nerve terminal activates CP-AMPARs in the principal cells of the medial nucleus of the trapezoid body in the brainstem. This leads to significant Ca2+ influx through these receptors before the onset of hearing at postnatal day 12 (P12). Using a selective open channel blocker of CP-AMPARs, IEM-1460, we estimate that ~80% of the AMPAR population are permeable to Ca2+ at immature P4-P5 synapses. However, after the onset of hearing, Ca2+ influx through these receptors was greatly reduced. We estimate that CP-AMPARs comprise approximately 40% and 33% of the AMPAR population at P18-P22 and P30-P34, respectively. By quantifying the rate of EPSC block by IEM-1460, we found an increased heterogeneity in glutamate release probability for adult-like calyces (P30-P34). Using tetraethylammonium (TEA), a presynaptic potassium channel blocker, we show that the apparent reduction of CP-AMPARs in more mature synapses is not a consequence of presynaptic action potential (AP) speeding. Finally, through postsynaptic AP recordings, we show that inhibition of CP-AMPARs reduces spike fidelity in juvenile synapses, but not in more mature synapses. We conclude that the expression of functional CP-AMPARs declines over early postnatal development in the calyx of Held synapse. [ABSTRACT FROM AUTHOR]

Background: Dalfampridine extended release (DAL) is a broad-spectrum voltage-gated potassium channel blocker that is indicated in multiple sclerosis to improve the nerve conduction of demyelinated axons. Seizures are a known side effect of DAL, which is contraindicated in patients with a history of epilepsy. Objective: Three cases of multiple sclerosis (MS) with de novo convulsive status epilepticus (CSE) probably related to dalfampridine administration are described. Methods: No patients had a history of seizures or renal impairment. Biological tests were normal. A brain magnetic resonance imaging (MRI) showed diffuse cortical and subcortical atrophy without active inflammatory lesions. Results: All three patients presented with CSE that was attributed to DAL and so was discontinued. Conclusion: These case reports illustrate that, aside from seizures, de novo CSE is a potential complication of MS patients treated with DAL. [ABSTRACT FROM AUTHOR]

Previous studies have investigated the cardiovascular activity of Gynura procumbens Merr. single-solvent extracts. The objective of this study was to evaluate the in vitro vasorelaxant properties and the underlying pharmacological mechanisms of serial extracts and fractions of Gynura procumbens (GP). The leaves of GP were serially extracted with petroleum ether, chloroform, methanol and water using the maceration method. Suspended aortic ring preparations were pre-contracted with phenylephrine (PE 1 µM), followed by cumulative addition of GP extracts (0.25–3 mg/mL). The petroleum ether extract (GPPE) was the most potent among the four extracts. Pre-incubation of endothelium-intact aorta with atropine (1 µM), indomethacin (10 µM), methylene blue (10 µM), propranolol (1 µM) and potassium channel blockers such as TEA (1 µM), glibenclamide (10 µM), 4-aminopyridine (1 µM) and barium chloride (10 mM) had no effect on GPPE-induced vasorelaxation. The vasorelaxant effect of GPPE was partly diminished by pretreatment of aortic rings preparations with l-NAME (10 µM) and even more so in endothelium-denuded aortic rings, indicating a minimal involvement of endothelium-dependent pathway in GPPE-induced vasorelaxation. The calcium-induced vasocontractions were antagonized significantly and concentration-dependently by GPPE in calcium free and high potassium medium. These results illustrate that Ca2+ antagonizing actions of GPPE in rat isolated aorta are comparable to that of verapamil and may be mainly responsible for its vasodilation effect. The antioxidant activity of GPPE supports its vasorelaxant effect by attenuating the production of deleterious free radicals and reactive oxygen species in the vasculature. [ABSTRACT FROM AUTHOR]

Background: Peripheral nerve compression and entrapment can be debilitating. Using a validated animal model of peripheral nerve compression, we examined the utility of 2 drugs approved for other uses in humans, 4-aminopyridine (4-AP) and erythropoietin (EPO), as treatments for surgically induced ischemia and as adjuvants to surgical decompression.Methods: Peripheral nerve compression was induced in wild-type mice by placing an inert silicone sleeve around the sciatic nerve. Decompression surgery was performed at 6 weeks with mice receiving 4-AP, EPO, or saline solution either during and after compression or only after decompression. A nerve conduction study and morphometric analyses were performed to compare the extent of the injury and the efficacy of the therapies, and the findings were subjected to statistical analysis.Results: During peripheral nerve compression, there was a progressive decline in nerve conduction velocity compared with that in sham-treatment animals, in which nerve conduction velocity remained normal (∼55 m/s). Mice treated with 4-AP or EPO during the compression phase had significantly smaller declines in nerve conduction velocity and increased plateau nerve conduction velocities compared with untreated controls (animals that received saline solution). Histomorphometric analyses of newly decompressed nerves (i.e., nerves that underwent decompression on the day that the mouse was sacrificed) revealed that both treated groups had significantly greater proportions of large (>5-µm) axons than the untreated controls. Following surgical decompression, all animals recovered to a normal baseline nerve conduction velocity by day 15; however, treatment significantly accelerated improvement (in both the 4-AP and the EPO group), even when it was only started after decompression. Histomorphometric analyses at 7 and 15 days following surgical decompression revealed significantly increased myelin thickness and significantly greater proportions of large axons among the treated animals.Conclusions: Both the 4-AP and the EPO-treated group demonstrated improvements in tissue architectural and electrodiagnostic measurements, both during and after peripheral nerve compression, compared with untreated mice.Clinical Relevance: Peripheral nerve decompression is one of the most commonly performed procedures in orthopaedic surgery. We believe that there is reason for some optimism about the translation of our findings to the clinical setting. Our findings in this murine model suggest that 4-AP and EPO may lessen the effects of nerve entrapment and that the use of these agents after decompression may speed and perhaps otherwise optimize recovery after surgery. [ABSTRACT FROM AUTHOR]

Aims/Introduction: A high‐carbohydrate diet is known to increase insulin secretion and induce obesity. However, whether or not a high‐carbohydrate diet affects β‐cell mass (BCM) has been little investigated. Materials and Methods: Both wild‐type (WT) mice and adenosine triphosphate‐sensitive potassium channel‐deficient (Kir6.2KO) mice were fed normal chow or high‐starch (ST) diets for 22 weeks. BCM and the numbers of islets were analyzed by immunohistochemistry, and gene expression levels in islets were investigated by quantitative real‐time reverse transcription polymerase chain reaction. MIN6‐K8 β‐cells were stimulated in solution containing various concentrations of glucose combined with nifedipine and glimepiride, and gene expression was analyzed. Results: Both WT and Kir6.2KO mice fed ST showed hyperinsulinemia and body weight gain. BCM, the number of islets and the expression levels of cyclinD2 messenger ribonucleic acid were increased in WT mice fed ST compared with those in WT mice fed normal chow. In contrast, no significant difference in BCM, the number of islets or the expression levels of cyclinD2 messenger ribonucleic acid were observed between Kir6.2KO mice fed normal chow and those fed ST. Incubation of MIN6‐K8 β‐cells in high‐glucose media or with glimepiride increased cyclinD2 expression, whereas nifedipine attenuated a high‐glucose‐induced increase in cyclinD2 expression. Conclusions: These results show that a high‐starch diet increases BCM in an adenosine triphosphate‐sensitive potassium channel‐dependent manner, which is mediated through upregulation of cyclinD2 expression. High starch diet increases β‐cell mass due to increasing the number of islets in a KATP channel‐dependent manner. [ABSTRACT FROM AUTHOR]

Summary: Objective: The high incidence of epileptic seizures in neonates and their frequent refractoriness to pharmacologic therapies require identification of new therapeutical options. Therefore, we investigated whether the modulatory effect of taurine on γ‐aminobutyric acid (GABA)A receptors can enhance the anticonvulsive potential of the GABAA receptor agonist muscimol and of the barbiturate pentobarbital. Methods: We performed field potential recordings in in toto hippocampus preparations of immature (postnatal days 4‐7) C57Bl/6 mouse pups. Spontaneous epileptiform activity was induced by the continuous presence of the potassium channel blocker 4‐aminopyridine and the glycinergic antagonist strychnine in Mg2+‐free solutions. Results: Bath application of 0.1 μmol/L muscimol increases the occurrence of recurrent epileptiform discharges, whereas they are significantly attenuated in a dose‐dependent manner by muscimol in concentrations between 0.5 and 5 μmol/L. Taurine at concentrations between 0.1 and 0.5 mmol/L induces a proconvulsive effect, but upon coapplication, it significantly augments the anticonvulsive effect of moderate muscimol doses (0.5‐1 μmol/L). In addition, the anticonvulsive effect of 100 and 200 μmol/L pentobarbital is increased significantly in the presence of 0.5 μmol/L taurine. Significance: These observations demonstrate that taurine can indeed enhance the anticonvulsive effects of muscimol and pentobarbital, suggesting that taurine may act as a positive modulator on GABAA receptors. Thus, interfering with the modulatory taurine binding site of GABAA receptors or the interstitial taurine concentration may provide new therapeutical options for anticonvulsive therapies in neonates. [ABSTRACT FROM AUTHOR]

Key points: The TASK‐1 channel gene (KCNK3) has been identified as a possible disease‐causing gene in heritable pulmonary arterial hypertension (PAH).In the present study, we show that novel mutated TASK‐1 channels, seen in PAH patients, have a substantially reduced current compared to wild‐type TASK‐1 channels.These mutated TASK‐1 channels are located at the plasma membrane to the same degree as wild‐type TASK‐1 channels.ONO‐RS‐082 and alkaline pH 8.4 both activate TASK‐1 channels but do not recover current through mutant TASK‐1 channels.We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK‐1 channels but does not recover current through mutant TASK‐1 channels. Pulmonary arterial hypertension (PAH) affects ∼15–50 people per million. KCNK3, the gene that encodes the two pore domain potassium channel TASK‐1 (K2P3.1), has been identified as a possible disease‐causing gene in heritable PAH. Recently, two new mutations have been identified in KCNK3 in PAH patients: G106R and L214R. The present study aimed to characterize the functional properties and regulation of wild‐type (WT) and mutated TASK‐1 channels and determine how these might contribute to PAH and its treatment. Currents through WT and mutated human TASK‐1 channels transiently expressed in tsA201 cells were measured using whole‐cell patch clamp electrophysiology. Localization of fluorescence‐tagged channels was visualized using confocal microscopy and quantified with in‐cell and on‐cell westerns. G106R or L214R mutated channels were located at the plasma membrane to the same degree as WT channels; however, their current was markedly reduced compared to WT TASK‐1 channels. Functional current through these mutated channels could not be restored using activators of WT TASK‐1 channels (pH 8.4, ONO‐RS‐082). The guanylate cyclase activator, riociguat, enhanced current through WT TASK‐1 channels; however, similar to the other activators investigated, riociguat did not have any effect on current through mutated TASK‐1 channels. Thus, novel mutations in TASK‐1 seen in PAH substantially alter the functional properties of these channels. Current through these channels could not be restored by activators of TASK‐1 channels. Riociguat enhancement of current through TASK‐1 channels could contribute to its therapeutic benefit in the treatment of PAH. Key points: The TASK‐1 channel gene (KCNK3) has been identified as a possible disease‐causing gene in heritable pulmonary arterial hypertension (PAH).In the present study, we show that novel mutated TASK‐1 channels, seen in PAH patients, have a substantially reduced current compared to wild‐type TASK‐1 channels.These mutated TASK‐1 channels are located at the plasma membrane to the same degree as wild‐type TASK‐1 channels.ONO‐RS‐082 and alkaline pH 8.4 both activate TASK‐1 channels but do not recover current through mutant TASK‐1 channels.We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK‐1 channels but does not recover current through mutant TASK‐1 channels. [ABSTRACT FROM AUTHOR]

Key points: The expression of miR‐1 is increased in lungs from the Hyp/Su5416 PAH rat model.Pulmonary artery smooth muscle cells from this animal model are more depolarized and show decreased expression and activity of voltage‐dependent potassium channel (Kv)1.5.miR‐1 directly targets Kv1.5 channels, reduces Kv1.5 activity and induces membrane depolarization.Antagomir‐1 prevents Kv1.5 channel downregulation and the depolarization induced by hypoxia/Su5416 exposition. Impairment of the voltage‐dependent potassium channel (Kv) plays a central role in the development of cardiovascular diseases, including pulmonary arterial hypertension (PAH). MicroRNAs are non‐coding RNAs that regulate gene expression by binding to the 3′‐untranslated region region of specific mRNAs. The present study aimed to analyse the effects of miR‐1 on Kv channel function in pulmonary arteries (PA). Kv channel activity was studied in PA from healthy animals transfected with miR‐1 or scrambled‐miR. Kv currents were studied using the whole‐cell configuration of the patch clamp technique. The characterization of the Kv1.5 currents was performed with the selective inhibitor DPO‐1. miR‐1 expression was increased and Kv1.5 channels were decreased in lungs from a rat model of PAH induced by hypoxia and Su5416. miR‐1 transfection increased cell capacitance, reduced Kv1.5 currents and induced membrane depolarization in isolated pulmonary artery smooth muscle cells. A luciferase reporter assay indicated that KCNA5, which encodes Kv1.5 channels, is a direct target gene of miR‐1. Incubation of PA with Su5416 and hypoxia (3% O2) increased miR‐1 and induced a decline in Kv1.5 currents, which was prevented by antagomiR‐1. In conclusion, these data indicate that miR‐1 induces pulmonary artery smooth muscle cell hypertrophy and reduces the activity and expression of Kv channels, suggesting a pathophysiological role in PAH. Key points: The expression of miR‐1 is increased in lungs from the Hyp/Su5416 PAH rat model.Pulmonary artery smooth muscle cells from this animal model are more depolarized and show decreased expression and activity of voltage‐dependent potassium channel (Kv)1.5.miR‐1 directly targets Kv1.5 channels, reduces Kv1.5 activity and induces membrane depolarization.Antagomir‐1 prevents Kv1.5 channel downregulation and the depolarization induced by hypoxia/Su5416 exposition. [ABSTRACT FROM AUTHOR]

Background: The protozoan Giardia lamblia is the causal agent of giardiasis, one of the main diarrheal infections worldwide. Drug resistance to common antigiardial agents and incidence of treatment failures have increased in recent years. Therefore, the search for new molecular targets for drugs against Giardia infection is essential. In protozoa, ionic channels have roles in their life cycle, growth, and stress response. Thus, they are promising targets for drug design. The strategy of ligand-protein docking has demonstrated a great potential in the discovery of new targets and structure-based drug design studies. Methods: In this work, we identify and characterize a new potassium channel, GiK, in the genome of Giardia lamblia. Characterization was performed in silico. Because its crystallographic structure remains unresolved, homology modeling was used to construct the three-dimensional model for the pore domain of GiK. The docking virtual screening approach was employed to determine whether GiK is a good target for potassium channel blockers. Results: The GiK sequence showed 24-50% identity and 50-90% positivity with 21 different types of potassium channels. The quality assessment and validation parameters indicated the reliability of the modeled structure of GiK. We identified 110 potassium channel blockers exhibiting high affinity toward GiK. A total of 39 of these drugs bind in three specific regions. Discussion: The GiK pore signature sequence is related to the small conductance calcium-activated potassium channels (SKCa). The predicted binding of 110 potassium blockers to GiK makes this protein an attractive target for biological testing to evaluate its role in the life cycle of Giardia lamblia and potential candidate for the design of novel antigiardial drugs. [ABSTRACT FROM AUTHOR]

KV3.1 blockers can serve as modulators of the rate of action potential firing in neurons with high rates of firing such as those of the auditory system. We studied the effects of several bioisosteres of N-alkylbenzenesulfonamides, and molecules derived from sulfanilic acid on KV3.1 channels, heterologously expressed in L-929 cells, using the whole-cell patch-clamp technique. Only the N-alkyl-benzenesulfonamides acted as open-channel blockers on KV3.1, while molecules analogous to PABA (p-aminobenzoic acid) and derived from sulfanilic acids did not block the channel. The IC50 of six N-alkyl-benzenesulfonamides ranged from 9 to 55 µM; and the Hill coefficient suggests the binding of two molecules to block KV3.1. Also, the effects of all molecules on KV3.1 were fully reversible. We look for similar features amongst the molecules that effectively blocked the channel and used them to model a blocker prototype. We found that bulkier groups and amino-lactams decreased the effectiveness of the blockage, while the presence of NO2 increased the effectiveness of the blockage. Thus, we propose N-alkylbenzenesulfonamides as a new class of KV3.1 channel blockers. [ABSTRACT FROM AUTHOR]

Photopharmacology is an area based on the creation of chemical compounds able to control the functioning of biological molecules using light. Photochromic compounds which activate or inhibit the activity of key cellular proteins, particularly ion channels, depending on the wavelength of the light, are powerful tools for noninvasive control of neural networks and, thus, for controlling the organs and behavior of animals. Photochromic substances can be divided into two main classes: (a) soluble photochromic ligands and (b) compounds covalently binding to target proteins, or tethered photochromic ligands. Potassium channel blockers, modulators of glutamate and GABA receptors, and cationic TRP channels have been created on this basis. Photopharmacology opens up the potential for controlling pain, restoring the photosensitivity of the retina, and controlling other physiological functions. This minireview will briefly present the main principles of the organization and actions of light-controlled switches, along with a description of photochromic chemical compounds able to modulate the activity of voltage-gated ion channels, and present preliminary investigations on the creation of photopharmacological compounds for therapeutic use. [ABSTRACT FROM AUTHOR]

The aim of the present experiment was to investigate the possible antiarrhythmic effects of dalfampridine in ouabain-induced arrhythmia in rats. Twenty-four male rats including the control and dalfampridine-incubated (100 µM to 10 mM) ouabain-stimulated (40 µM) groups were used. After induction of anesthesia, the atria were isolated and the time of onset of arrhythmia and asystole were recorded. The contractile force of atria was also measured. Dalfampridine at concentration of 1 mM significantly postponed the onset of arrhythmia and asystole compared to control group (p ≤ .05). Ouabain significantly increased the atrial beating rate in control group (p ≤ .05), while pretreatment of isolated atria with dalfampridine reversed this effect. Incubation of isolated atria with ouabain did not alter the contractile force in both control- and dalfampridine-treated groups (p > .05). It is concluded that dalfampridine might possess antiarrhythmic properties in reducing the atrial arrhythmias. [ABSTRACT FROM AUTHOR]

Key points: Medullo‐spinal CSF contacting neurones (CSF‐cNs) located around the central canal are conserved in all vertebrates and suggested to be a novel sensory system intrinsic to the CNS.CSF‐cNs receive GABAergic inhibitory synaptic inputs involving ionotropic GABAA receptors, but the contribution of metabotropic GABAB receptors (GABAB‐Rs) has not yet been studied.Here, we indicate that CSF‐cNs express functional GABAB‐Rs that inhibit postsynaptic calcium channels but fail to activate inhibitory potassium channel of the Kir3‐type.We further show that GABAB‐Rs localise presynaptically on GABAergic and glutamatergic synaptic inputs contacting CSF‐cNs, where they inhibit the release of GABA and glutamate.Our data are the first to address the function of GABAB‐Rs in CSF‐cNs and show that on the presynaptic side they exert a classical synaptic modulation whereas at the postsynaptic level they have an atypical action by modulating calcium signalling without inducing potassium‐dependent inhibition. Medullo‐spinal neurones that contact the cerebrospinal fluid (CSF‐cNs) are a population of evolutionary conserved cells located around the central canal. CSF‐cN activity has been shown to be regulated by inhibitory synaptic inputs involving ionotropic GABAA receptors, but the contribution of the G‐protein coupled GABAB receptors has not yet been studied. Here, we used a combination of immunofluorescence, electrophysiology and calcium imaging to investigate the expression and function of GABAB‐Rs in CSF‐cNs of the mouse brainstem. We found that CSF‐cNs express GABAB‐Rs, but their selective activation failed to induce G protein‐coupled inwardly rectifying potassium (GIRK) currents. Instead, CSF‐cNs express primarily N‐type voltage‐gated calcium (CaV2.2) channels, and GABAB‐Rs recruit Gβγ subunits to inhibit CaV channel activity induced by membrane voltage steps or under physiological conditions by action potentials. Moreover, using electrical stimulation, we indicate that GABAergic inhibitory (IPSCs) and excitatory glutamatergic (EPSCs) synaptic currents can be evoked in CSF‐cNs showing that mammalian CSF‐cNs are also under excitatory control by glutamatergic synaptic inputs. We further demonstrate that baclofen reversibly reduced the amplitudes of both IPSCs and EPSCs evoked in CSF‐cNs through a presynaptic mechanism of regulation. In summary, these results are the first to demonstrate the existence of functional postsynaptic GABAB‐Rs in medullar CSF‐cNs, as well as presynaptic GABAB auto‐ and heteroreceptors regulating the release of GABA and glutamate. Remarkably, postsynaptic GABAB‐Rs associate with CaV but not GIRK channels, indicating that GABAB‐Rs function as a calcium signalling modulator without GIRK‐dependent inhibition in CSF‐cNs. Key points: Medullo‐spinal CSF contacting neurones (CSF‐cNs) located around the central canal are conserved in all vertebrates and suggested to be a novel sensory system intrinsic to the CNS.CSF‐cNs receive GABAergic inhibitory synaptic inputs involving ionotropic GABAA receptors, but the contribution of metabotropic GABAB receptors (GABAB‐Rs) has not yet been studied.Here, we indicate that CSF‐cNs express functional GABAB‐Rs that inhibit postsynaptic calcium channels but fail to activate inhibitory potassium channel of the Kir3‐type.We further show that GABAB‐Rs localise presynaptically on GABAergic and glutamatergic synaptic inputs contacting CSF‐cNs, where they inhibit the release of GABA and glutamate.Our data are the first to address the function of GABAB‐Rs in CSF‐cNs and show that on the presynaptic side they exert a classical synaptic modulation whereas at the postsynaptic level they have an atypical action by modulating calcium signalling without inducing potassium‐dependent inhibition. [ABSTRACT FROM AUTHOR]

Complete eradication of Helicobacter pylori is important for preventing the development of gastric cancer. The outcome of H. pylori eradication therapy is mainly dependent on bacterial susceptibility to antimicrobial agents and potent neutralization of intragastric pH across 24 h, especially when using acid-sensitive antimicrobial agents such as clarithromycin (CLR), amoxicillin and sitafloxacin. However, conventional regimens comprising twice-daily doses (bid) of proton pump inhibitors (PPIs) are generally insufficient for maintaining the required gastric acid secretion for 24 h for successful eradication in all H. pylori -positive patients. Further, the increasing prevalence of CLR-resistant strains with each year has led to a decrease in eradication rates of first-line PPI- and CLR-containing therapies in developed countries, including Japan. In 2015, the potassium-competitive acid blocker vonoprazan (VPZ) became clinically available in Japan. VPZ competitively inhibits H+/K+-ATPase activity more potently than PPIs (e.g., omeprazole, lansoprazole, rabeprazole, pantoprazole, and esomeprazole). Therefore, a VPZ-containing H. pylori eradication regimen is expected to increase the eradication rate compared with conventional regimens containing a standard dose of PPI. In fact, a recent meta-analysis that investigated the efficacy of first-line eradication therapy showed that a VPZ-containing regimen achieved a higher eradication rate than a PPI-containing regimen. While the Maastricht V/Florence Consensus Report recommends selecting a bismuth or non-bismuth quadruple therapy and concomitant therapy for patients living in areas with high prevalence of CLR resistance, a VPZ-containing regimen demonstrates effectiveness for patients infected with CLR-resistant strains and patients living in areas where the prevalence of CLR-resistant strains is >15%. As a next step, studies are needed to determine the factors affecting the clinical outcome of VPZ-containing therapy and optimal VPZ-containing alternative regimens for tailored treatments. In this review, we summarize the advantages and disadvantages of VPZ in H. pylori eradication therapy. [ABSTRACT FROM AUTHOR]

Introduction: Patient expectation of treatment outcome is one of the primary mechanisms underlying the placebo effect. In multiple sclerosis trials with symptomatic treatments, a robust placebo effect is observed, which might be related to patient expectations. The aim of this study was to evaluate whether patient expectations regarding fampridine treatment influence the clinical response after 4 weeks and 6 months of treatment.Materials and Methods: We designed and carried out a prospective study from June 2015 to August 2017. Before treatment, patients completed a questionnaire including a scale evaluating their expectations regarding the treatment. The effect of baseline positive expectancy on the response status after 4 weeks and 6 months of treatment was analyzed through univariable and, when applicable, multivariable analysis.Results: A total of 47 consecutive patients were included in the study. At week 4, 37 (78.7%) patients were classified as responders; a one-point increase in the positive expectancy questionnaire was significantly associated with a fourfold increase in the likelihood of being a responder [OR = 4.020 (95% CI 1.082-14.933); p = 0.038]. At 6 months, 43 patients completed follow-up. The number of responders decreased to 28; at this point, positive expectancy at baseline was no longer associated with response status.Conclusion: Baseline positive expectancy regarding fampridine was determinant of the clinical response after 4 weeks of treatment. However, in the long term, fampridine efficacy was not dependent on expectations prior to treatment. [ABSTRACT FROM AUTHOR]