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Reports of Chagas disease are increasing in non-endemic populations across the globe. Apart from vector eradication and prevention efforts by public health organizations, current pharmacological interventions are sparse and show important side effects. In this issue of the BJP, Andrade et al. elegantly demonstrate a new pharmacological paradigm whereby Trypanosoma cruzi host cell invasion requires significant cross-talk between receptors for kinins and endothelins. It is shown, for example, that acting via both ETA and ETB receptors, endothelin-1 (ET-1) cooperates with the (TLR2/CXCR2/B2 kinin receptor) complex to activate inflammatory processes in response to invading trypomastigotes. This study by Andrade et al. prompts, however, several important questions, summarized in this Commentary, such as the putative role of chymase-dependent production of ET-1, the contentious protective role of ACE inhibitors in Chagasic patients, the unexplored role of de novo formed B1 receptors for kinins triggered by cytokines and the putative role of compartmentalized calcium pools in host cell invasion by trypomastigotes. LINKED ARTICLE This article is a commentary on Andrade et al., pp. 1333-1347 of this issue. To view this paper visit [ABSTRACT FROM AUTHOR]

1. Acoustic rhinometry is a relatively new method for objectively assessing nasal airway patency. In this paper we compare acoustic rhinometry with active posterior rhinomanometry. 2. Twenty normal healthy volunteers underwent nasal challenge with either histamine or bradykinin, 100 micrograms to 1000 micrograms, and responses were assessed by acoustic rhinometry. A further 20 subjects received identical nasal challenges and responses were assessed by active posterior rhinomanometry. 3. On a subsequent occasion, the subjects challenged previously with histamine, were given the selective H1-receptor antagonist, cetirizine, 10 mg orally, 3 h before repeat nasal challenge with histamine, 100-1000 micrograms. Again, responses were assessed by active posterior rhinomanometry and acoustic rhinometry. 4. The acoustic reflection measurements and the nasal airway resistance measurements showed comparable, significant dose-related changes in nasal patency to both histamine and bradykinin. Pretreatment with cetirizine blocked the histamine-induced change in nasal patency as measured by both methods. 5. We conclude that acoustic rhinometry has a number of advantages over posterior rhinomanometry. It is quick to perform, requires minimal subject co-operation and gives a reliable objective, measurement of dose-related changes in nasal airway patency before and after pharmacological treatment.

This paper describes the solution conformation of the vasoactive peptide hormone des-Arg9-bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe). 1. By ¹H-NMR spectroscopy we studied des-Arg9-bradykinin and its fragments bradykinin-(1-5), bradykinin-(1-6) in aqueous solution as a function of pH (titration) and in dimethylsulfoxide solution at two ionic states (cation and neutral ion species). 2. The preferred solution conformation which is most strongly stabilized in dimethylsulfoxide in the neutral ion species includes a distorted β-turn II involving the N-terminal sequence of Pro²-Pro²-Gly4-Phe5 and most likely a C7-type bend in the C-terminal part Ser-Pro-Phe. 3. A complete series of analogous ([Alan]des Arg9-bradykinin, with n = 1, 2 . . . 8) was then investigated by circular dichroism and ¹H-NMR spectroscopy in order to study the conformational role played by cach residue and to delineate the local and the long-range effects on conformation brought about by the Xaa→Ala substitutions. Chosen spectral parameters (circular dichroic spectra, chemical shift variations and vicinal coupling constants) characteristics of the preferred solution conformation of the native sequence of des-Arg9-bradykinin are followed from analogue to analogue. The important conformational role of the arginine-1 side chain and its positive charge and the spatial proximity of the N-terminal and C-terminal groups, i.e. the folded structure of the peptide can be inferred from these data. 4. A comparison of the biological activities of the analogues with the conformative pertubatins caused by the chemical alterations shows des-Arg9-bradykinin conformation and receptor affinity to be equally sensitive to single-residue substitutions. The correct orientation of the arginine-1 side chain, the precise geometry of the turn involving residues 2-5 and of the C-terminal Pro-Phe sequence are of primary importance. [ABSTRACT FROM AUTHOR]

Objective: The role of neurogenic inflammation in pathogenesis of chronic rhinitis is well known. However, very little is known about its importance in pathogenesis of nasal polyposis (NP), especially in form of NP which appears as a part of aspirin‐exacerbated respiratory disease (AERD). The aim of this study was to examine the concentrations of neuropeptides substance P (SP) and bradykinin (BK) in nasal secretions of patients with NP. Methods: Fourteen patients with NP as a part of AERD with mild persistent asthma, 14 patients with NP without aspirin sensitivity, and 14 control subjects without nasal inflammation (C) entered this cross‐sectional study. Clinical parameters (symptoms, endoscopic, and radiological findings) were assessed. The concentrations of SP and BK were measured in the nasal secretion samples using commercial human enzyme immunoassay kits. Results: The concentration of SP in nasal secretions was significantly higher in NP patients without aspirin sensitivity and AERD patients compared to controls (p =.022; p <.0001, respectively), but higher in AERD than in non‐AERD patients (p =.018). The level of BK in nasal fluid was higher in non‐AERD and AERD NP patients than in controls (p <.0001; p <.0001, respectively), but also higher in AERD than in non‐AERD patients (p <.0001). We found high positive correlations between BK in nasal fluid and Lund–Mackay computed tomography (CT) score in both non‐AERD and AERD groups of NP patients. Conclusion: Our results suggest more intense release of SP and BK from the nasal mucosa in patients with AERD than in patients with NP who do not have aspirin sensitivity. The strong correlation between concentration of BK in nasal secretions and CT score suggests that BK in nasal fluid could be used as a marker for disease severity as measured by the Lund–Mackay score. [ABSTRACT FROM AUTHOR]

Background and Purpose: Bradykinin (BK‐(1–9)) is an endogenous nonapeptide involved in multiple physiological and pathological processes. Peptide fragments of bradykinin are believed to be biologically inactive. We have now tested the two major peptide fragments of bradykinin in human and animals. Experimental Approach BK peptides were quantified by MS in male rats. NO release was quantified from human, mouse and rat cells loaded with DAF‐FM. Rat aortic rings were used to measure vascular reactivity. Changes in BP and HR were measured in conscious male rats. To evaluate pro‐inflammatory effects both vascular permeability and nociception were measured in adult mice. Key Results: BK‐(1–7) and BK‐(1–5) are produced in vivo from BK‐(1–9). Both peptides induced NO production in all cell types tested. However, unlike BK‐(1–9), NO production elicited by BK‐(1–7) or BK‐(1–5) was not inhibited by B1 or B2 receptor antagonists. BK‐(1–7) and BK‐(1–5) induced concentration‐dependent vasorelaxation of aortic rings, without involvement of B1 or B2 receptors. Intravenous or intra‐arterial administration of BK‐(1–7) or BK‐(1–5) induced similar hypotensive response in vivo. Nociceptive responses of BK‐(1–7) and BK‐(1–5) were reduced compared to BK‐(1–9), and no increase in vascular permeability was observed for BK‐(1–9) fragments. Conclusions and Implications: BK‐(1–7) and BK‐(1–5) are endogenous peptides present in plasma. BK‐related peptide fragments show biological activity, not mediated by B1 or B2 receptors. These BK fragments could constitute new, active components of the kallikrein–kinin system. [ABSTRACT FROM AUTHOR]

Background and Purpose: Superoxide anions can reduce the bioavailability and actions of endothelium‐derived NO. In human resistance‐sized arteries, endothelium‐dependent vasodilatation can be mediated by H2O2 instead of NO. Here, we tested the hypothesis that in resistance arteries from patients with cardiovascular disease, endothelium‐dependent vasodilatation is mediated by a reactive oxygen species and not impaired by oxidative stress. Experimental Approach Small arteries were isolated from biopsies of the parietal pericardium of patients undergoing elective cardiothoracic surgery and were studied using immunohistochemical and organ chamber techniques. Key Results: NO synthases 1, 2 and 3, superoxide dismutase 1 and catalase proteins were observed in the microvascular wall. Relaxing responses to bradykinin were endothelium dependent. During submaximal depolarization‐induced contraction, bradykinin‐mediated relaxations were inhibited by inhibitors of NO synthases (NOS) and soluble guanylyl cyclase (sGC) but not by scavengers of NO or HNO, inhibitors of cyclooxygenases, neuronal NO synthase, superoxide dismutase or catalase, or by exogenous catalase. During contraction stimulated by endothelin‐1, these relaxations were not reduced by any of these interventions except DETCA, which caused a small reduction. Conclusion and Implications: In resistance arteries from patients with cardiovascular disease, endothelium‐dependent relaxations seem not to be mediated by NO, HNO or H2O2, although NOS and sGC can be involved. These vasodilator responses continue during excessive oxidative stress. [ABSTRACT FROM AUTHOR]

In view of their permeability to small peptides, it has been postulated that human erythrocytes may play a role in terminating the action of some circulating peptide hormones. Work using classical paper chromatographic techniques for detecting free amino acids indicated that the octapeptide, des-(Arg9)-bradykinin, enters these cells and its amino-terminal arginine residue is released by cytosolic aminopeptidase-P. We have used 1H NMR to monitor directly the release of arginine from bradykinin. The hydrolytic reaction rate in hemolysates, with an initial peptide concentration of 13.0 mmol l-1 was 6.5 mmol (1 packed red cell)-1 h-1. But no reaction was evident after a 4.5-h incubation with intact cells, thus contradicting the earlier suggestion that erythrocytes are involved in the primary inactivation of this hormone. This is consistent with our previous findings that the pentapeptide leu-enkephalin fails to enter human erythrocytes but that its lower-order degradation products may do so.

Background and Purpose: The serine and cysteine peptidase inhibitor, BbCI, isolated from Bauhinia bauhinioides seeds, is similar to the classical plant Kunitz inhibitor, STI, but lacks disulphide bridges and methionine residues. BbCI blocks activity of the serine peptidases, elastase (K(iapp) 5.3 nM) and cathepsin G (K(iapp) 160.0 nM), and the cysteine peptidase cathepsin L (K(iapp) 0.2 nM). These three peptidases play important roles in the inflammatory process.Experimental Approach: We measured the effects of BbCI on paw oedema and on leucocyte accumulation in pleurisy, both induced by carrageenan. Leucocyte-endothelial cell interactions in scrotal microvasculature in Wistar rats were investigated using intravital microscopy. Cytokine levels in pleural exudate and serum were measured by elisa.Key Results: Pretreatment of the animals with BbCI (2.5 mg·kg(-1)), 30 min before carrageenan-induced inflammation, effectively reduced paw oedema and bradykinin release, neutrophil migration into the pleural cavity. The number of rolling, adhered and migrated leucocytes at the spermatic fascia microcirculation following carrageenan injection into the scrotum were reduced by BbCI pretreatment. Furthermore, levels of the rat chemokine cytokine-induced neutrophil chemo-attractant-1 were significantly reduced in both pleural exudates and serum from animals pretreated with BbCI. Levels of interleukin-1β or tumour necrosis factor-α, however, did not change.Conclusions and Implications: Taken together, our data suggest that the anti-inflammatory properties of BbCI may be useful in investigations of other pathological processes in which human neutrophil elastase, cathepsin G and cathepsin L play important roles. [ABSTRACT FROM AUTHOR]

Background and Purpose: Statins (HMG CoA reductase inhibitors) have beneficial effects independent of reducing cholesterol synthesis and this includes their ability to acutely activate endothelial nitric oxide synthase (eNOS). The mechanism by which this occurs is largely unknown and thus we characterized the pathways by which statins activate NOS, including involvement of scavenger receptor-B1 (SR-B1), which is expressed in endothelial cells and maintains cholesterol concentrations.Experimental Approach: Nitric oxide production was monitored in bovine aortic endothelial cells (BAECs) exposed to lovastatin (LOV) or pravastatin (PRA) for 10-20 min, alone or following pre-exposure to the end product of HMG-CoA reductase (mevalonate), G protein inhibitors (pertussis/cholera toxins), phospholipase C (PLC) inhibitor (U-73122), or intracellular and extracellular calcium chelators - BAPTA-AM and EGTA (respectively), or a function blocking antibody to SR-B1.Key Results: Both statins increased NO production in a rapid, dose-dependent and HMG-CoA reductase-independent manner. Inhibiting Gi protein or PLC almost completely blocked statin-induced NO generation. Additionally, removing extracellular calcium inhibited statin-induced NO production. COS-7 cells co-transfected with eNOS and SR-B1 increased NO production when exposed to LOV or high-density lipoprotein (HDL), an agonist of SR-B1. These effects were not observed in COS-7 cells with eNOS alone or co-transfected with bradykinin receptor 2, indicating specificity for SR-B1. Further, pretreatment of BAEC with blocking antibody for SR-B1 blocked NO responses to statins and HDL.Conclusions and Implications: LOV and PRA acutely activate eNOS through pathways that include the cell surface receptor SR-B1, Gi protein, phosholipase C and entry of extracellular calcium into endothelial cells. [ABSTRACT FROM AUTHOR]

Background and Purpose: Small (SK(Ca) or K(Ca)2) and intermediate (IK(Ca) or K(Ca)3.1) conductance calcium-activated potassium channels are involved in regulation of vascular tone and blood pressure. The present study investigated whether NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime) and CyPPA (cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine), which are selective openers of SK(Ca) and IK(Ca) channels and of SK(Ca)2 and SK(Ca)3 channels, respectively, enhance endothelium-dependent vasodilatation in porcine retinal arterioles.Experimental Approach: In porcine retinal arterioles, SK(Ca)3 and IK(Ca) protein localization was examined by immunolabelling. Endothelial cell calcium was measured by fluorescence imaging. For functional studies, arterioles with internal diameters of 116 +/- 2 microm (n = 276) were mounted in microvascular myographs for isometric tension recordings.Key Results: SK(Ca)3 and IK(Ca) protein was localized in the endothelium. Bradykinin, but not NS309 or CyPPA increased endothelial cell calcium. Pre-incubation with NS309 or CyPPA enhanced bradykinin relaxation without changing endothelial cell calcium. This enhanced relaxation was abolished by blocking SK(Ca) channels with apamin. In the presence of NS309 or CyPPA, mainly inhibition of NO synthase with asymmetric dimethylarginine, but also inhibition of cyclooxygenase with indomethacin, reduced bradykinin relaxation. Bradykinin relaxation was completely abolished by NO synthase and cyclooxygenase inhibition together with a NO scavenger, oxyhaemoglobin.Conclusions and Implications: In porcine retinal arterioles, bradykinin increases endothelial cell calcium leading to activation of SK(Ca) and IK(Ca) channels. Without altering endothelial cell calcium, NS309 and CyPPA open SK(Ca) channels that enhance NO-mediated bradykinin relaxations. These results imply that opening SK(Ca) channels improves endothelium-dependent relaxation and makes this channel a potential target for treatments aimed at restoring retinal blood flow. [ABSTRACT FROM AUTHOR]

Background and Purpose: Bradykinin (BK) and B2 receptors have been implicated in the pathophysiology of osteoarthritis (OA), and synovitis is one of its hallmarks. Here, the selective B2 receptor antagonists MEN16132 and icatibant have been pharmacologically characterized in human synovial cells.Experimental Approach: Radioligand and functional studies (inositol phosphate (IP) accumulation, interleukin (IL)-6 and IL-8 release) were performed in cultured synoviocytes.Key Results: [3H]-BK saturation studies indicated receptor density (Bmax) and K(d) values of 121,550 sites per cell and 1.14 nM respectively. In synoviocytes, MEN16132 (pK(I) 8.9) was threefold more potent than icatibant (pK(I) 8.4). Both antagonists showed competitive antagonism in the BK-induced IP assay (control EC50 0.45 nM), with pK(B) values of 9.9 (MEN16132) and 8.1 (icatibant). 24h incubation with BK induced IL-6 (EC50 216 nM) and IL-8 (EC50 53 nM) release. Both MEN16132 (IL-6: pIC50 8.1; IL-8: pIC50 8.4) and icatibant (IL-6: pIC50 6.6; IL-8: pIC50 6.7) completely prevented this BK-induced release. Indomethacin did not affect the basal or the IL-6/IL-8 release induced by BK, whereas nordihydroguaiaretic acid decreased the basal release, although BK still increased IL-6 and IL-8 production. BK-induced IL-8 release was attenuated by inhibitors of phospholipase C (U73122), p38 (SB203580), JNK (SP600125), ERK 1/2 (PD98059) MAPKs, phosphoinositide 3-kinase (LY294002), NF-kappaB (BAY-117085) and by the glucocorticoid dexamethasone.Conclusions and Implications: Bradykinin via B2 receptors can participate in inflammatory events in synovitis. MEN16132 is a highly potent B2 receptor antagonist capable of blocking pro-inflammatory responses to BK evoked in human synoviocytes. [ABSTRACT FROM AUTHOR]

Background and Purpose: A peptide bradykinin (BK) B(2) receptor agonist partially resistant to degradation, B-9972, down-regulates this receptor subtype. We have used another recently described non-peptide agonist, compound 47a, as a tool to study further the effects of metabolically more stable and thus persistent, agonists of the BK B(2) receptor on signalling, desensitization and down-regulation of this receptor.Experimental Approach and Key Results: Compound 47a was a partial agonist at the B(2) receptor in the human umbilical vein, where it shared with B-9972 a very slow relaxation on washout, and in HEK 293 cell lines expressing tagged forms [myc, green fluorescent protein (GFP)] of the rabbit B(2) receptor. Compound 47a desensitized the umbilical vein to BK. In the cellular systems, the inactivation-resistant agonists induced [Ca(2+)](i) transients as brief as those of BK but affected other functions with a longer duration than BK [12 h; receptor endocytosis, endosomal beta-arrestin(1/2) translocation, protein kinase C-dependent extracellular signal-regulated kinases (ERK)1/2 phosphorylation and c-Fos expression]. The B(2) receptor-GFP was degraded in cells exposed to B-9972 or compound 47a for 12 h. The non-peptide B(2) receptor antagonist LF 16-0687 prevented all effects of compound 47a, which were also absent in cells lacking recombinant B(2) receptors.Conclusion and Implications: Inactivation-resistant agonists revealed a long-lasting assembly of the agonist-B(2) receptor-beta-arrestin complexes in endosomal structures and induce 'biased signalling' (in terms of activation of ERK and c-Fos) as a function of time. Further, B-9972 and compound 47a, unlike BK, efficiently down-regulated BK B(2) receptors. [ABSTRACT FROM AUTHOR]

While the role of the brain kallikrein-kinin system in the development of various pathological processes, such as oedema formation following brain injury or induction of central hypertonia has generated major interest, the possible role of this system in nociceptive processing has received little attention. In their present paper, Mortari et al. (2007) show that bradykinin B2 receptor activation in the brain by the bradykinin analogue, Thr6-bradykinin, isolated from the venom of the social wasp, Polybia occidentalis potently reduces acute, noxious heat-evoked reflex responses in naive rats. The unknown underlying mechanism of this powerful antinociceptive effect reminds us that the supraspinal antinociceptive system is still a “black box” in many aspects and awaits thorough investigation.British Journal of Pharmacology (2007) 151, 721–722; doi:10.1038/sj.bjp.0707274; published online 29 May 2007 [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID‐19), caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), continues to be a world‐wide pandemic with overwhelming socioeconomic impact. Since inflammation is one of the major causes of COVID‐19 complications, the associated molecular mechanisms have been the focus of many studies to better understand this disease and develop improved treatments for patients contracting SARS‐CoV‐2. Among these, strong emphasis has been placed on pro‐inflammatory cytokines, associating severity of COVID‐19 with so‐called "cytokine storm." More recently, peptide bradykinin, its dysregulated signaling or "bradykinin storm," has emerged as a primary mechanism to explain COVID‐19‐related complications. Unfortunately, this important development may not fully capture the main molecular players that underlie the disease severity. To this end, in this focused review, several lines of evidence are provided to suggest that in addition to bradykinin, two closely related vasoactive peptides, substance P and neurotensin, are also likely to drive microvascular permeability and inflammation, and be responsible for development of COVID‐19 pathology. Furthermore, based on published experimental observations, it is postulated that in addition to ACE and neprilysin, peptidase neurolysin (Nln) is also likely to contribute to accumulation of bradykinin, substance P and neurotensin, and progression of the disease. In conclusion, it is proposed that "vasoactive peptide storm" may underlie severity of COVID‐19 and that simultaneous inhibition of all three peptidergic systems could be therapeutically more advantageous rather than modulation of any single mechanism alone. [ABSTRACT FROM AUTHOR]

Background: Bradykinin-mediated angioedema (AE) is a complication associated with thrombolysis for acute ischemic stroke. Risk factors are unknown and management is discussed.Objectives: To clarify risk factors associated with bradykinin-mediated AE after thrombolysis for acute ischemic stroke.Methods: In a case-control study conducted at a French reference centre for bradykinin angiœdema, patients with thrombolysis for acute ischemic stroke and a diagnosis of bradykinin-mediated angiœdema, were compared to controls treated with thrombolysis treatment without angiœdema.Results: Fifty-three thrombolysis-related AE were matched to 106 control subjects. The sites of attacks following thrombolysis for ischemic stroke mainly included tongue (34/53, 64%) and lips (26/53, 49%). The upper airways were involved in 37 (70%) cases. Three patients required mechanical ventilation. Patients with bradykinin-mediated angiœdema were more frequently women [33 (62%) vs. 44 (42%); P = 0.01], had higher frequency of prior ischemic stroke [12 (23%) vs. 9 (8%); P = 0.01], hypertension [46 (87%) vs. 70 (66%); P = 0.005], were more frequently treated with angiotensin-converting enzyme inhibitor [37 (70%) vs. 28 (26%); P < 0.001] and were more frequently hospitalized in intensive care medicine [ICU; 11 (21%) vs. 5 (5%); P = 0.004]. In multivariate analysis, factors associated with thrombolysis-related AE were female sex [odds ratio (OR), 3.04; 95% confident interval (CI), 1.32-7.01; P = 0.009] and treatment with angiotensin-converting enzyme inhibitors [(OR), 6.08; 95% (CI), 2.17-17.07; P < 0.001].Conclusions: This case-control study points out angiotensin-converting enzyme inhibitors and female sex as risk factors of bradykinin AE associated with thrombolysis for ischemic stroke. [ABSTRACT FROM AUTHOR]

Background and Purpose: Bradykinin may induce vasoconstriction in selected vessels or under specific experimental conditions. We hypothesized that inflammatory stimuli, such as endotoxin challenge, may induce the dimerization of AT1 /B2 receptors, altering the vascular effects of bradykinin.Experimental Approach: Wistar rats received LPS (1 mg·kg-1 , i.p.) and were anaesthetized for assessment of BP. Mesenteric resistance arteries were used in organ baths and subjected to co-immunoprecipitation and Western blot analyses.Key Results: At 24 and 48 hr after LPS, bradykinin-induced hypotension was followed by a sustained increase in BP, which was not found in non-endotoxemic animals. The B2 receptor antagonist Hoe-140 fully blocked the responses to bradykinin. The pressor effect of bradykinin was not prevented by prazosin, an α1 -adrenoceptor antagonist, but it was inhibited by the AT1 receptor antagonist losartan or the Rho-kinase inhibitor Y-27632. Endotoxemic rats also displayed enhanced pressor responses to angiotensin II, which were blocked by Hoe-140. Co-immunoprecipitation isolated using anti-B2 or anti-AT1 receptor antibodies showed that resistance arteries presented augmented levels of the AT1 /B2 receptor complexes at 24 hr after LPS injection. The presence of AT1 /B2 receptor heterodimers did correlate with the development of losartan-sensitive contractile responses to bradykinin and potentiation of angiotensin II-induced contraction, which was prevented by Hoe-140.Conclusions and Implications: Endotoxin challenge is a stimulus for AT1 /B2 receptor heterodimerization in native vessels and shifts the B2 receptor-dependent vascular effect of bradykinin to a more complex pathway, which also depends on AT1 receptors and their intracellular signalling pathways. [ABSTRACT FROM AUTHOR]

Background and Purpose: Glucagon-like peptide-1 (GLP-1) is an incretin hormone that regulates insulin biosynthesis and secretion in a glucose-dependent manner and has been reported to induce vasodilatation. Here, we examined the possible vasorelaxant effect of GLP-1 and its underlying mechanisms.Experimental Approach: Rat mesenteric arteries (diameter ≈ 200-400 μm) and human s.c. arteries were mounted in microvascular myographs for isometric tension recordings. The effect of GLP-1 on vascular responses was examined under normoglycaemic conditions and at high glucose concentrations.Key Results: In rat mesenteric arteries and human s.c. arteries without branches, physiological concentrations (1-100 nM) of GLP-1(7-36) and liraglutide failed to cause relaxation or affect contractions evoked by electrical field stimulation. In contrast to GLP-1(7-36), liraglutide induced relaxations antagonized by the GLP-1 receptor antagonist, exendin-(9-39), in branched mesenteric arteries. In contrast to liraglutide, GLP-1 leftward shifted the concentration relaxation curves for bradykinin in s.c. arteries from patients with peripheral arterial disease, an effect resistant to exendin-(9-39). Under normoglycaemic conditions, neither GLP-1 nor liraglutide affected ACh relaxation in rat mesenteric arteries. In arteries exposed to 40 mM glucose, GLP-1, in contrast to liraglutide, potentiated ACh-induced relaxation by a mechanism that was not antagonized by exendin-(9-39). GLP-1 decreased superoxide levels measured with dihydroethidium in rat mesenteric arteries exposed to 40 mM glucose.Conclusions and Implications: GLP-1 receptors are involved in the liraglutide-induced relaxation of branched arteries, under normoglycaemic conditions, while GLP-1 inhibition of vascular superoxide levels contributes to GLP-1 receptor-independent potentiation of endothelium-dependent vasodilatation in hyperglycaemia. [ABSTRACT FROM AUTHOR]

A conference paper about the non-cholinergic component of the bronchoconstrictor response to bradykinin (BK) is presented. It investigates the involvement of leukotrienes, tachykinins and the peptidases, angiotensin converting enzyme and neutral endopeptidase. It shows that the bronchoconstrictor response to BK is not mediated by leukotrienes or tachykinins.

A conference paper about the selectivity of the ascorbate blockade in the ciliary vascular bed and the occurrence of the blockade in the porcine left anterior descending coronary artery is presented. It reveals that bradykinin induces concentration-dependent and endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation. It concludes that ascorbate-induced blockade of EDHF-mediated vasodilatation in the bovine ciliary circulation appears to be selective.

A conference paper about the ability of large pulmonary arteries to utilize an endothelium-derived hyperpolarizing factor (EDHF) after removing nitric oxide or inhibiting guanylyl cyclase is presented. It discusses the effect of potassium channel blockers on the concentration response curve for bradykinin-induced relaxation. It concludes that bradykinin induces relaxation in this study.

According to the National Health and Nutrition Examination Survey 2012, one third of antihypertensive prescriptions in the United States in the past decade were for angiotensin-converting enzyme inhibitors (ACEIs). An important and serious side effect of ACEIs is angioedema caused by a reduction in bradykinin degradation. In a national medical chart abstraction study conducted at the US Veterans Affairs Health Care System in 2008, 0.20% of ACEI initiators developed angioedema while on the medication. The angiotensin-converting enzyme is a part of the renin-angiotensin system that converts angiotensin I to angiotensin II. It is additionally responsible for the degradation of bradykinin, which is generated from high molecular weight kininogen by kallikrein. Via bradykinin 2 receptors, bradykinin affects vascular permeability and stimulates the release of substance P, which is a peptide that causes vasodilation and fluid extravasation into tissues. Inhibition of the angiotensin-converting enzyme and subsequent blockade of bradykinin degradation is thought to be a likely explanation for ACEI-induced angioedema. Studies have shown that blacks, women, and smokers are at an increased risk for ACEI-induced angioedema. A 2005 study identified black race, history of drug rash, age older than 65 years, and seasonal allergies as independent risk factors for angioedema related to enalapril. Angioedema may occur at any time during treatment with ACEIs and may continue after the medication is discontinued. The degree of ACEI-angiotensin receptor blocker angioedema cross-reactivity is difficult to determine from the literature. However, multiple studies have reported relatively low rates of native angioedema with angiotensin receptor blockers (approximately half that of ACEIs, or 0.1%) and a low incidence of cross-reactivity (<10%). Common treatments for angioedema, such as antihistamines and glucocorticoids, have not been shown to be effective in ACEI-induced angioedema. However, medications that have been used for acute treatment of hereditary angioedema and target the factors that cause ACEI-mediated angioedema are being explored. [ABSTRACT FROM AUTHOR]

Somatostatin is a cyclic peptide, released in the gastrointestinal system and the central nervous system, where it is involved in the regulation of cognitive and sensory functions, motor activity and sleep. It is a substrate of insulin-degrading enzyme (IDE), as well as a modulator of its activity and expression. In the present study, we have investigated the modulatory role of somatostatin on IDE activity at 37 °C and pH 7.3 for various substrates [i.e. insulin, β-amyloid (Aβ)1-40 and bradykinin], aiming to quantitatively characterize the correlation between the specific features of the substrates and the regulatory mechanism. Functional data indicate that somatostatin, in addition to the catalytic site of IDE (being a substrate), is also able to bind to two additional exosites, which play different roles according to the size of the substrate and its binding mode to the IDE catalytic cleft. In particular, one exosite, which displays high affinity for somatostatin, regulates only the interaction of IDE with larger substrates (such as insulin and Aβ1-40) in a differing fashion according to their various modes of binding to the enzyme. A second exosite, which is involved in the regulation of enzymatic processing by IDE of all substrates investigated (including a 10-25 amino acid long amyloid-like peptide, bradykinin and somatostatin itself, which had been studied previously), probably acts through the alteration of an 'open-closed' equilibrium. [ABSTRACT FROM AUTHOR]

Aims: It is not known whether concomitant use of aspirin might attenuate the beneficial effects of mineralocorticoid receptor antagonists (MRAs). The purpose of this subgroup analysis was to explore the interaction between baseline aspirin treatment and the effect of eplerenone on the primary efficacy outcomes (composite of hospitalization for heart failure or cardiovascular mortality), its components, and safety markers [estimated glomerular filtration rate (eGFR), systolic blood pressure (SBP), and serum potassium >5.5 mmol/L] in the Eplerenone in Mild Patients Hospitalization and SurvIval Study in Heart Failure trial (EMPHASIS-HF).Methods and Results: Patients with chronic heart failure, reduced ejection fraction (HFREF), and mild symptoms were enrolled in EMPHASIS-HF. We evaluated baseline characteristics according to aspirin use. We explored the interaction between aspirin and eplerenone, using Cox proportional hazards models providing adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) and P-values for interaction. Of the 2737 patients randomized, 1605 patients (58.6%) were taking aspirin. The beneficial effects of eplerenone on the primary endpoint were similar in patients not treated (adjusted HR 0.59, 95% CI 0.46-0.75) or treated (adjusted HR 0.71, 95% CI 0.59-0.87) with aspirin at baseline (interaction P-value = 0.19). We did not observe any significant modification of the safety markers by aspirin that was clinically meaningful.Conclusion: Aspirin use in patients with chronic systolic heart failure and mild symptoms did not substantially reduce the overall beneficial effects of the MRA eplerenone contrary to what has been described in some studies with ACE inhibitors. [ABSTRACT FROM AUTHOR]

Background and Purpose: We tested the hypothesis that in resistance arteries from cardiovascular disease (CVD) patients, effects of an endothelium-dependent vasodilator depend on the contractile stimulus.Experimental Approach: Arteries dissected from parietal pericardium of cardiothoracic surgery patients were studied by myography and imaging techniques. Segments were sub-maximally contracted by K(+) , the TxA2 analogue U46619 or endothelin-1 (ET-1).Key Results: Relaxing effects of Na-nitroprusside were comparable, but those of bradykinin (BK) were bigger in the presence of ET-1 compared with K(+) or U46619. BK-induced relaxation was (i) abolished by L-NAME in K(+) -contracted arteries, (ii) partly inhibited by L-NAME in the presence of U46619 and (iii) not altered by indomethacin, L-NAME plus inhibitors of small and intermediate conductance calcium-activated K(+) channels, but attenuated by catalase, in ET-1-contracted arteries. This catalase-sensitive relaxation was unaffected by inhibitors of NADPH oxidases or allopurinol. Exogenous H2 O2 caused a larger relaxation of ET-1-induced contractions than those evoked by K(+) or U46619 in the presence of inhibitors of other endothelium-derived relaxing factors. Catalase-sensitive staining of cellular ROS with CellROX Deep Red was significantly increased in the presence of both 1 μM BK and 2 nM ET-1 but not either peptide alone.Conclusions and Implications: In resistance arteries from patients with CVD, exogenous ET-1 shifts the mediator of relaxing responses to the endothelium-dependent vasodilator BK from NO to H2 O2 and neither NADPH oxidases, xanthine oxidase nor NOS appear to be involved in this effect. This might have consequences for endothelial dysfunction in conditions where intra-arterial levels of ET-1 are enhanced. [ABSTRACT FROM AUTHOR]

Presents a correction to the article "Inhibitory Effect of BIBN4096BS on Cephalic Vasodilatation Induced by CGRP or Transcranial Electrical Stimulation in the Rat," by Kenneth A. Petersen, Steffen Birk, Henri Doods, Lars Edvinsson and Jes Olesen that was previously published in a 2004 issue of the periodical "British Journal of Pharmacology."

Background and Purpose Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. Experimental Approach The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells ( PCASMCs). Key Results At a concentration without direct effect on vascular tone, kaempferol (3 × 10−6 M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by Nω-nitro- L-arginine methyl ester, an inhibitor of NO synthase (10−4 M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10−6 M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10−3 M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel ( KCa1.1; 10−7 M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. Conclusions and Implications The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa1.1 channels. [ABSTRACT FROM AUTHOR]

In patients with acute myocardial infarction, timely reperfusion is essential to limit infarct size. However, reperfusion also adds to myocardial injury. Brief episodes of ischaemia/reperfusion in the myocardium or on organ remote from the heart, before or shortly after sustained myocardial ischaemia effectively reduce infarct size, provided there is eventual reperfusion. Such conditioning phenomena have been established in many experimental studies and also translated to humans. The underlying signal transduction, that is the molecular identity of triggers, mediators and effectors, is not clear yet in detail, but several extracellular signalling molecules, such as adenosine, bradykinin and opioids, have been identified to contribute to cardioprotection by conditioning manoeuvres. Several trials have attempted the translation of cardioprotection by such autacoids into a clinical scenario of myocardial ischaemia and reperfusion. Adenosine and its selective agonists reduced infarct size in a few studies, but this benefit was not translated into improved clinical outcome. All studies with bradykinin or drugs which increase bradykinin's bioavailability reported reduced infarct size and some of them also improved clinical outcome. Synthetic opioid agonists did not result in a robust infarct size reduction, but this failure of translation may relate to the cardioprotective properties of the underlying anaesthesia per se or of the comparator drugs. The translation of findings in healthy, young animals with acute coronary occlusion/reperfusion to patients of older age, with a variety of co-morbidities and co-medications, suffering from different scenarios of myocardial ischaemia/reperfusion remains a challenge. Linked Articles This article is part of a themed section on Conditioning the Heart - Pathways to Translation. To view the other articles in this section visit [ABSTRACT FROM AUTHOR]

Themolecular and cellularmechanisms governing cell motility and directedmigration in response to the neuropeptide bradykinin are largely unknown. Here, we demonstrate that human glioma cells whose migration is guided by bradykinin generate bleb-like protrusions. We found that activation of the B2 receptor leads to a rise in free Ca2+ from internal stores that activates actomyosin contraction and subsequent cytoplasmic flow into protrusions forming membrane blebs. Furthermore Ca2+ activates Ca2+-dependent K+ and Cl- channels, which participate in bleb regulation. Treatment of gliomas with bradykinin in situ increased glioma growth by increasing the speed of cell migration at the periphery of the tumour mass. To test if bleb formation is related to bradykinin-promoted glioma invasion we blocked glioma migration with blebbistatin, a blocker of myosin kinase II, which is necessary for proper bleb retraction. Our findings suggest a pivotal role of bradykinin during glioma invasion by stimulating amoeboid migration of glioma cells. [ABSTRACT FROM AUTHOR]

The decrease in ER Ca SP 2+ sp is sensed by STIM1 proteins, which aggregate and move closer to the plasma membrane, and activate Orai1 channels by protein-protein interaction (Woo I et al i . 2018) (Fig. The resulting decrease in ER Ca2+ content is sensed by the Ca2+ binding protein STIM1, which activates plasma Orai1 channels in the plasma membrane by protein-protein interaction. [Extracted from the article]

Background and Purpose Palmitoylethanolamide ( PEA) is an endogenous fatty acid amide displaying anti-inflammatory and analgesic actions. To investigate the molecular mechanism responsible for these effects, the ability of PEA and of pain-inducing stimuli such as capsaicin ( CAP) or bradykinin ( BK) to influence intracellular calcium concentrations ([ Ca2+]i) in peripheral sensory neurons, has been assessed in the present study. The potential involvement of the transcription factor PPARα and of TRPV1 channels in PEA-induced effects was also studied. Experimental Approach [ Ca2+]i was evaluated by single-cell microfluorimetry in differentiated F11 cells. Activation of TRPV1 channels was assessed by imaging and patch-clamp techniques in CHO cells transiently-transfected with rat TRPV1 cDNA. Key Results In F11 cells, PEA (1-30 μ M) dose-dependently increased [ Ca2+]i. The TRPV1 antagonists capsazepine (1 μ M) and SB-366791 (1 μ M), as well as the PPARα antagonist GW-6471 (10 μ M), inhibited PEA-induced [ Ca2+]i increase; blockers of cannabinoid receptors were ineffective. PEA activated TRPV1 channels heterologously expressed in CHO cells; this effect appeared to be mediated at least in part by PPARα. When compared with CAP, PEA showed similar potency and lower efficacy, and caused stronger TRPV1 currents desensitization. Sub-effective PEA concentrations, closer to those found in vivo, counteracted CAP- and BK-induced [ Ca2+]i transients, as well as CAP-induced TRPV1 activation. Conclusions and Implications Activation of PPARα and TRPV1 channels, rather than of cannabinoid receptors, largely mediate PEA-induced [ Ca2+]i transients in sensory neurons. Differential TRPV1 activation and desensitization by CAP and PEA might contribute to their distinct pharmacological profile, possibly translating into potentially relevant clinical differences. [ABSTRACT FROM AUTHOR]

Background and Purpose: Inflammatory pain is triggered by activation of pathways leading to the release of mediators such as bradykinin, prostaglandins, interleukins, ATP, growth factors and protons that sensitize peripheral nociceptors. The activation of acid-sensitive ion channels (ASICs) may have particular relevance in the development and maintenance of inflammatory pain. ASIC3 is of particular interest due to its restricted tissue distribution in the nociceptive primary afferent fibres and its high sensitivity to protons.Experimental Approach: To examine the contribution of ASIC3 to the development and maintenance of muscle pain and inflammatory pain, we studied the in vivo efficacy of a selective ASIC3 inhibitor, APETx2, in rats.Key Results: Administration of APETx2 into the gastrocnemius muscle prior to the administration of low pH saline prevented the development of mechanical hypersensitivity, whereas APETx2 administration following low-pH saline was ineffective in reversing hypersensitivity. The prevention of mechanical hypersensitivity produced by acid administration was observed whether APETx2 was applied via i.m. or i.t. routes. In the complete Freund's adjuvant (CFA) inflammatory pain model, local administration of APETx2 resulted in a potent and complete reversal of established mechanical hypersensitivity, whereas i.t. application of APETx2 was ineffective.Conclusions and Implications: ASIC3 contributed to the development of mechanical hypersensitivity in the acid-induced muscle pain model, whereas ASIC3 contributed to the maintenance of mechanical hypersensitivity in the CFA inflammatory pain model. The contribution of ASIC3 to established hypersensitivity associated with inflammation suggests that this channel may be an effective analgesic target for inflammatory pain states. [ABSTRACT FROM AUTHOR]

Thimet oligopeptidase (EC 3.4.24.15) is a zinc(II) endopeptidase implicated in the processing of numerous physiological peptides. Although its role in selecting and processing peptides is not fully understood, it is believed that flexible loop regions lining the substrate-binding site allow the enzyme to conform to substrates of varying structure. This study describes mutant forms of thimet oligopeptidase in which Gly or Tyr residues in the 599–611 loop region were replaced, individually and in combination, to elucidate the mechanism of substrate selection by this enzyme. Decreases in kcat observed on mutation of Tyr605 and Tyr612 demonstrate that these residues contribute to the efficient cleavage of most substrates. Modeling studies showing that a hinge-bend movement brings both Tyr612 and Tyr605 within hydrogen bond distance of the cleaved peptide bond supports this role. Thus, molecular modeling studies support a key role in transition state stabilization of this enzyme by Tyr605. Interestingly, kinetic parameters show that a bradykinin derivative is processed distinctly from the other substrates tested, suggesting that an alternative catalytic mechanism may be employed for this particular substrate. The data demonstrate that neither Tyr605 nor Tyr612 is necessary for the hydrolysis of this substrate. Relative to other substrates, the bradykinin derivative is also unaffected by Gly mutations in the loop. This distinction suggests that the role of Gly residues in the loop is to properly orientate these Tyr residues in order to accommodate varying substrate structures. This also opens up the possibility that certain substrates may be cleaved by an open form of the enzyme. [ABSTRACT FROM AUTHOR]

Background and Purpose: Kinins are acknowledged as important regulators of intestinal function during inflammation; however, their effects on human intestinal ion transport have not been reported. Here, we used muscle-stripped human colonic tissue and cultured T(84)-cell monolayers to study bradykinin (BK) actions on human intestinal ion transport.Experimental Approach: Ion transport was measured as changes in short-circuit current (I(sc)) across colonic epithelia mounted in Ussing chambers.Key Results: In intact tissue, there was a distinct polarity to BK-elicited I(sc) responses. Whereas basolateral BK stimulated sustained responses (EC(50)=0.5+/-0.1 microM), those to apical BK were more rapid and transient (EC(50)=4.1+/-1.2 nM). In T(84) cells, responses to both apical and basolateral BK were similar to those seen upon apical addition to intact tissues. Cross-desensitization between apical and basolateral domains was not observed. BK-induced responses were largely due to Cl(-) secretion as shown by their sensitivity to bumetanide and removal of Cl(-) from the bathing solution. Studies using selective agonists and antagonists indicate responses to BK are mediated by B(2) receptors. Finally, responses to basolateral BK in intact tissues were inhibited by tetrodotoxin (1 microM), atropine (1 microM), capsaicin (100 microM) and piroxicam (10 microM). BK-stimulated prostaglandin (PG)E(2) release from colonic tissue.Conclusions: BK stimulates human colonic Cl(-) secretion by activation of apical and basolateral B(2) receptors. Responses to apical BK reflect a direct action on epithelial cells, whereas those to basolateral BK are amplified by stimulation of enteric nerves and PG synthesis. [ABSTRACT FROM AUTHOR]

Our previous studies have shown that angiotensin II and reactive oxygen species in the paraventricular nucleus (PVN) modulate the cardiac sympathetic afferent reflex (CSAR). The present study was designed to demonstrate more conclusively that the PVN is an important component of the central neurocircuitry of the CSAR. In anaesthetized Sprague–Dawley rats with sinoaortic denervation and cervical vagotomy, renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were continuously recorded. The CSAR was evaluated by the response of the RSNA to epicardial application of bradykinin or capsaicin. Bilateral microinjection of the anaesthetic, lignocaine, into the PVN abolished the CSAR without significant effects on the baseline RSNA and MAP, whilel-glutamate, which excites the neurons in the PVN, enhanced the CSAR and increased the baseline RSNA and MAP. Bilateral electrolytic lesions of the PVN irreversibly abolished the CSAR without significant effects on the baseline RSNA and MAP. Bilateral selective lesions of the neurons in the PVN with kainic acid induced rapid and great increases in both RSNA and MAP which returned to nearly normal levels in 60 min. At the 90th minute after kainic acid, epicardial application of bradykinin or capsaicin failed to induce the CSAR. These results indicate that inhibition or lesion of the PVN abolishes the CSAR, but excitation of the neurons in the PVN enhances the CSAR, suggesting that the PVN is an important component of the central neurocircuitry of the CSAR. [ABSTRACT FROM AUTHOR]

Background and purpose:We investigated whether or not kinin receptors play a role in diabetic blood–retinal barrier breakdown, which is a leading cause of vision loss.Experimental approach:Blood–retinal barrier breakdown was quantified using Evans blue, and expression of kinin B1 receptor mRNA was measured using quantitative reverse transcrition-PCR. Diabetic rats (streptozotocin (STZ), 65 mg kg−1) received a single intraocular injection of bradykinin (BK) or des-Arg9-BK, alone, or in combination with antagonists for B1 (des-Arg10-Hoe140, R-715) and/or B2 (Hoe140) receptors, given intraocularly or intravenously (i.v.).Key results:In control rats, BK (0.1–10 nmol) dose-dependently increased plasma extravasation, which was inhibited by Hoe140 (0.2 nmol), whereas des-Arg9-BK (0.1 and 1 nmol) was without effect. B1 receptor mRNA was markedly increased in retinas of diabetic rats, and this was prevented by N-acetyl-L-cysteine (1 g kg−1 day−1 for 7 days). Plasma extravasation in retinas of STZ-diabetic rats was higher than in controls and enhanced by des-Arg9-BK. Response to des-Arg9-BK was inhibited by intraocular or i.v. injection of B1 receptor antagonists. Diabetes-induced plasma extravasation was inhibited only by a combination of des-Arg10-Hoe140 and Hoe 140 (100 nmol kg−1, i.v. 15 min earlier) or by R-715 (1 μmol kg−1, i.v.) injected daily for 7 days.Conclusions and implications:Kinin B1 receptors are upregulated in retinas of STZ-diabetic rats through a mechanism involving oxidative stress. Both kinin B1 and B2 receptors contribute to increased plasma extravasation in diabetic retinopathy. Chronic inhibition of both kinin receptors, possibly with antioxidant adjuvants, may be a novel therapeutic strategy for diabetic retinopathy.British Journal of Pharmacology (2008) 154, 136–143; doi:10.1038/bjp.2008.48; published online 3 March 2008 [ABSTRACT FROM AUTHOR]

Ischaemic preconditioning limits the damage induced by subsequent ischaemia/reperfusion (I/R). However, preconditioning is of little practical use as the onset of an infarction is usually unpredictable. Recently, it has been shown that the heart can be protected against the extension of I/R injury if brief (10-30 sec.) coronary occlusions are performed just at the beginning of the reperfusion. This procedure has been called postconditioning (PostC). It can also be elicited at a distant organ, termed remote PostC, by intermittent pacing (dyssynchronyinduced PostC) and by pharmacological interventions, that is pharmacological PostC. In particular, brief applications of intermittent bradykinin or diazoxide at the beginning of reperfusion reproduce PostC protection. PostC reduces the reperfusion-induced injury, blunts oxidant-mediated damages and attenuates the local inflammatory response to reperfusion. PostC induces a reduction of infarct size, apoptosis, endothelial dysfunction and activation, neutrophil adherence and arrhythmias. Whether it reduces stunning is not clear yet. Similar to preconditioning, PostC triggers signalling pathways and activates effectors implicated in other cardioprotective manoeuvres. Adenosine and bradykinin are involved in PostC triggering. PostC triggers survival kinases (RISK), including Aκt and extracellular signal-regulated kinase (ERK). Nitric oxide, via nitric oxide synthase and nonenzymatic production, cyclic guanosine monophosphate (cGMP) and protein kinases G (PKG) participate in Post C. Post C-induced protection also involves an early redox-sensitive mechanism, and mitochondrial adenosine- 5′-triphosphate (ATP)-sensitive K+ and PKC activation. Protective pathways activated by PostC appear to converge on mitochondrial permeability transition pores, which are inhibited by acidosis and glycogen synthase kinase-3β (GSK-3β). In conclusion, the first minutes of reperfusion represent a window of opportunity for triggering the aforementioned mediators which will in concert lead to protection against reperfusion injury. Pharmacological PostC and possibly remote PostC may have a promising future in clinical scenario. [ABSTRACT FROM AUTHOR]

Background and Purpose: Inhibition of bradykinin metabolizing enzymes (BMEs) can cause acute angioedema, as demonstrated in a recent clinical trial in patients administered the antihypertensive, omapatrilat. However, the relative contribution of specific BMEs to this effect is unclear and confounded by the lack of a predictive pre-clinical model of angioedema.Experimental Approach: Rats were instrumented to record blood pressure and heart rate; inhibitors were infused for 35 min and bradykinin was infused during the last 5 min to elicit hypotension, as a functional marker of circulating bradykinin and relative angioedema risk.Key Results: In the presence of omapatrilat bradykinin produced dose-dependent hypotension, an effect abolished by B(2) blockade. In the presence of lisinopril (ACE inhibitor), but not candoxatril (NEP inhibitor) or apstatin (APP inhibitor), bradykinin also elicited hypotension. Lisinopril-mediated hypotension was unchanged with concomitant blockade of NEP or NEP/DPPIV (candoxatril+A-899301). However, hypotension was enhanced upon concomitant blockade of APP and further intensified in the presence of NEP inhibition to values not different from omapatrilat alone.Conclusions and Implications: We demonstrated that bradykinin is degraded in vivo with an enzyme rank-efficacy of ACE>APP>>NEP or DPPIV. These results suggest the effects of omapatrilat are mediated by inhibition of three BMEs, ACE/APP/NEP. However, dual inhibition of ACE/NEP or ACE/NEP/DPPIV elicits no increased risk of angioedema compared to ACE inhibition alone. Thus, novel BME inhibitors must display no activity against APP to avoid angioedema risk due to high prevalence of ACE inhibitor therapy in patients with diabetes and cardiovascular disease. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to determine whether reactive oxygen species (ROS) in the paraventricular nucleus (PVN) mediate both the cardiac sympathetic afferent reflex (CSAR) and angiotensin II-induced CSAR enhancement in chronic heart failure (CHF) rats. CSAR was evaluated from the responses of renal sympathetic nerve activity (RSNA) to epicardial application of bradykinin. In both CHF and sham-operated rats, PVN microinjection of the superoxide anion scavengers tempol or tiron almost abolished the CSAR, but the superoxide dismutase inhibitor DETC potentiated the CSAR. PVN pretreatment with tempol or tiron abolished, whereas DETC augmented, the angiotensin II-induced CSAR enhancement. In CHF rats, superoxide anion and malondialdehyde (MDA) levels in the PVN were increased, but were normalized by the AT1 receptor antagonist losartan. PVN microinjection of tempol decreased superoxide anion and MDA levels, but epicardial application of bradykinin or PVN microinjection of angiotensin II increased superoxide anion and MDA to higher levels in CHF rats than in sham-operated rats. These results indicate that ROS in the PVN mediates the CSAR and the effect of angiotensin II in the PVN on the CSAR in both CHF and sham-operated rats. Increased ROS in the PVN are involved in the enhanced CSAR in CHF. [Copyright &y& Elsevier]

Background and purpose:Diabetes causes sensory polyneuropathy with associated pain in the form of tactile allodynia and thermal hyperalgesia which are often intractable and resistant to current therapy. This study tested the beneficial effects of the non-peptide and orally active kinin B1 receptor antagonist SSR240612 against tactile and cold allodynia in a rat model of insulin resistance.Experimental approach:Rats were fed with 10% D-glucose for 12 weeks and effects of orally administered SSR240612 (0.3–30 mg kg−1) were determined on the development of tactile and cold allodynia. Possible interference of SSR240612 with vascular oxidative stress and pancreatic function was also addressed.Key results:Glucose-fed rats exhibited tactile and cold allodynia, increases in systolic blood pressure and higher plasma levels of insulin and glucose, at 12 weeks. SSR240612 blocked tactile and cold allodynia at 3 h (ID50=5.5 and 7.1 mg kg−1, respectively) in glucose-fed rats but had no effect in control rats. The antagonist (10 mg kg−1) had no effect on plasma glucose and insulin, insulin resistance (HOMA index) and aortic superoxide anion production in glucose-fed rats.Conclusions and implications:We provide the first evidence that the B1 receptors are involved in allodynia in an experimental rat model of insulin resistance. Allodynia was alleviated by SSR240612 most likely through a direct inhibition of B1 receptors affecting spinal cord and/or sensory nerve excitation. Thus, orally active non-peptide B1 receptor antagonists should have clinical therapeutic potential in the treatment of sensory polyneuropathy.British Journal of Pharmacology (2007) 152, 280–287; doi:10.1038/sj.bjp.0707388; published online 9 July 2007 [ABSTRACT FROM AUTHOR]

Background and purpose:In this work, a neuroactive peptide from the venom of the neotropical wasp Polybia occidentalis was isolated and its anti-nociceptive effects were characterized in well-established pain induction models.Experimental approach:Wasp venom was analysed by reverse-phase HPLC and fractions screened for anti-nociceptive activity. The structure of the most active fraction was identified by electron-spray mass spectrometry (ESI-MS/MS) and it was further assessed in two tests of anti-nociceptive activity in rats: the hot plate and tail flick tests.Key Results:The most active fraction contained a peptide whose structure was Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg-OH, which corresponds to that of Thr6-BK, a bradykinin analogue. This peptide was given by i.c.v. injection to rats. In the tail flick test, Thr6-BK induced anti-nociceptive effects, approximately twice as potent as either morphine or bradykinin also given i.c.v. The anti-nociceptive activity of Thr6-BK peaked at 30 min after injection and persisted for 2 h, longer than bradykinin. The primary mode of action of Thr6-BK involved the activation of B2 bradykinin receptors, as anti-nociceptive effects of Thr6-BK were antagonized by a selective B2 receptor antagonist.Conclusions and implications:Our data indicate that Thr6-BK acts through B2 bradykinin receptors in the mammalian CNS, evoking antinociceptive behaviour. This activity is remarkably different from that of bradykinin, despite the structural similarities between both peptides. In addition, due to the increased metabolic stability of Thr6-BK, relative to that of bradykinin, this peptide could provide a novel tool in the investigation of kinin pathways involved with pain.British Journal of Pharmacology (2007) 151, 860–869; doi:10.1038/sj.bjp.0707275; published online 29 May 2007 [ABSTRACT FROM AUTHOR]

Background and purpose:α-Humulene and trans-caryophyllene are sesquiterpene compounds identified in the essential oil of Cordia verbenacea which display topical and systemic anti-inflammatory effects in different experimental models. However, the molecular mechanisms through which they exert their anti-inflammatory activity still remain unclear. Here, we evaluate the effects of α-humulene and trans-caryophyllene on the acute inflammatory responses elicited by LPS.Experimental approach:The biological activities of α-humulene and trans-caryophyllene were investigated in a model of acute inflammation in rat paw, induced by LPS and characterized by paw oedema, neutrophil recruitment, cytokine production, activation of MAP kinases and NF-κB and up-regulated expression of kinin B1 receptors.Key results:Treatment with either α-humulene or trans-caryophyllene effectively reduced neutrophil migration and activation of NF-κB induced by LPS in the rat paw. However, only α-humulene significantly reduced the increase in TNF-α and IL-1β levels, paw oedema and the up-regulation of B1 receptors following treatment with LPS. Both compounds failed to interfere with the activation of the MAP kinases, ERK, p38 and JNK.Conclusions and Implications:Both α-humulene and trans-caryophyllene inhibit the LPS-induced NF-κB activation and neutrophil migration, although only α-humulene had the ability to prevent the production of pro-inflammatory cytokines TNF-α and IL-1β and the in vivo up-regulation of kinin B1 receptors. These data provide additional molecular and functional insights into the beneficial effects of the sesquiterpenes α-humulene and trans-caryophyllene isolated from the essential oil of Cordia verbenacea as agents for the management of inflammatory diseases.British Journal of Pharmacology (2007) 151, 618–627; doi:10.1038/sj.bjp.0707270; published online 30 April 2007 [ABSTRACT FROM AUTHOR]

Background and purpose:We have previously shown that melatonin inhibits bradykinin-induced NO production by endothelial cells in vitro. The purpose of this investigation was to extend this observation to an in vivo condition and to explore the mechanism of action of melatonin.Experimental approach:RT-PCR assays were performed with rat cultured endothelial cells. The putative effect of melatonin upon arteriolar tone was investigated by intravital microscopy while NO production by endothelial cells in vitro was assayed by fluorimetry, and intracellular Ca2+ measurements were assayed by confocal microscopy.Key results:No expression of the mRNA for the melatonin synthesizing enzymes, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase, or for the melatonin MT2 receptor was detected in microvascular endothelial cells. Melatonin fully inhibited L-NAME-sensitive bradykinin-induced vasodilation and also inhibited NO production induced by histamine, carbachol and 2-methylthio ATP, but did not inhibit NO production induced by ATP or α, β-methylene ATP. None of its inhibitory effects was prevented by the melatonin receptor antagonist, luzindole. In nominally Ca2+-free solution, melatonin reduced intracellular Ca2+ mobilization induced by bradykinin (40%) and 2-methylthio ATP (62%) but not Ca2+ mobilization induced by ATP.Conclusions and implications:We have confirmed that melatonin inhibited NO production both in vivo and in vitro. In addition, the melatonin effect was selective for some G protein-coupled receptors and most probably reflects an inhibition of Ca2+ mobilization from intracellular stores.British Journal of Pharmacology (2007) 151, 195–205. doi:10.1038/sj.bjp.0707225; published online 20 March 2007 [ABSTRACT FROM AUTHOR]

Background and Purpose: Prenatal patency of ductus arteriosus is maintained by prostaglandin (PG) E(2), possibly along with nitric oxide (NO) and carbon monoxide (CO), and cyclooxygenase (COX) deletion upregulates NO. Here, we have examined enzyme source and action of NO for ductus patency and whether NO and CO are upregulated by deletion of, respectively, heme oxygenase 2 (HO-2) and COX1 or COX2.Experimental Approach: Experiments were performed in vitro and in vivo with wild-type and gene-deleted, near-term mouse fetuses.Key Results: N(G)-nitro-L-arginine methyl ester (L-NAME) contracted the isolated ductus and its effect was reduced by eNOS, but not iNOS, deletion. L-NAME contraction was not modified by HO-2 deletion. Zinc protoporphyrin (ZnPP) also contracted the ductus, an action unaffected by deletion of either COX isoform. Bradykinin (BK) relaxed indomethacin-contracted ductus similarly in wild-type and eNOS-/- or iNOS-/-. BK relaxation was suppressed by either L-NAME or ZnPP. However, it reappeared with combined L-NAME and ZnPP to subside again with K(+) increase or K(+) channel inhibition. In vivo, the ductus was patent in wild-type and NOS-deleted fetuses. Likewise, no genotype-related difference was noted in postnatal closure.Conclusions and Implications: NO, formed mainly via eNOS, regulates ductal tone. NO and CO cooperatively mediate BK-induced relaxation in the absence of PGE(2). However, in the absence of PGE(2), NO and CO, BK induces a relaxant substance behaving as an endothelium-derived hyperpolarizing factor. Ductus patency is, therefore, sustained by a cohort of agents with PGE(2) and NO being preferentially coupled for reciprocal compensation. [ABSTRACT FROM AUTHOR]

The aim of this study was to measure the direct release of nitric oxide (NO) from the porcine mitral valve using a NO microelectrode. Furthermore, the expression and localization of endothelial nitric oxide synthase (eNOS) in the mitral valve was studied using immunohistochemistry, Western blotting and RT-PCR. Results show that bradykinin increases NO release from mitral valves (ΔBradykinin: 33.71 ± 10.41 nm NO, P < 0.001, n = 10), whereas N-nitro-l-arginine methyl esther (l-NAME) decreases NO release when compared with basal level (Δl-NAME: 82.69 ± 15.66 nm NO, P < 0.005, n = 4). Both protein and mRNA expression of eNOS in mitral valves and in isolated valvular endothelial cells suggest that the NO release is mainly associated with the mitral valve endothelium. It is concluded that direct NO release from porcine mitral valves coincides with eNOS expression. This study documents useful techniques for investigations into the role of local NO release in mitral valve diseases. [ABSTRACT FROM AUTHOR]

Background and purpose:A bradykinin (BK) B2 receptor (B2R) antagonist, B-9870 (CU201), has been proposed to behave as a ‘biased agonist’ at B2Rs and to exert anti-neoplasic effects. It was unclear whether these effects were determined by the activation of B2Rs by the drug. B-9870 was evaluated for antagonism or stimulation of several responses mediated by the rabbit B2R or B1 receptor (B1R); its anti-proliferative activity was also characterized.Experimental approach and key results:B-9870 was an insurmountable B2R antagonist in the rabbit jugular vein contractility assay, but a partial agonist in HEK 293 cells expressing the rabbit B2R or a green fluorescent protein (GFP) conjugate of the latter (ERK1/2 phosphorylation, [Ca2+]i, [3H]-arachidonate release, endocytosis). The agonist-like effects of B-9870 were inhibited by the B2R antagonist LF 16.0687 and absent in untransfected cells. In addition, B-9870 was a surmontable antagonist of the rabbit B1R in the aorta contractility assay, and blocked Lys-des-Arg9-BK-induced ERK1/2 phosphorylation in HEK 293 cells expressing a fluorescent B1R conjugate. B-9870 inhibited the growth of MDA-MB-231 cells. The latter effect was not influenced by B1R or B2R antagonists and was not apoptotic. MDA-MB-231 cells expressed a small population of B2Rs but no B1Rs; they responded to BK (small calcium transients) and B-9870 behaved as an antagonist.Conclusion and implications:B-9870 is a dual B1R and B2R antagonist with confirmed stimulating effects at the B2R in high expression systems only. Its cell type-specific anti-proliferative effect occurs at a high concentration, independently from kinin receptors and apoptosis.British Journal of Pharmacology (2007) 150, 369–379. doi:10.1038/sj.bjp.0706982; published online 18 December 2006 [ABSTRACT FROM AUTHOR]

Background and purpose:The aim was to characterize the recently discovered non-peptide antagonist MEN16132 at the mouse B2 receptor, relative to other antagonists.Experimental approach:[3H]-BK binding experiments used mouse lung and ileum tissue membranes and antagonist potency was measured in the isolated ileum contractility assay.Key results:Two BK binding sites resulted from saturation and homologous competition experiments. A role for the B1 receptor was excluded because of the poor affinity of B1 receptor ligands (pIC50 <5). MEN16132, and the other reference antagonists, inhibited only one portion of BK specific binding, and the rank order of potency was (pIC50): Icatibant (lung 10.7; ileum 10.2)=MEN11270 (lung 10.4; ileum 9.9)=MEN16132 (lung 10.5; ileum 9.9). > LF16-0687 (lung 8.9; ileum 8.8) > FR173657 (lung 8.6; ileum 8.2). BK homologous curves performed with lung membranes after treatment with the antagonist MEN16132 or Icatibant (10 nM) displayed only the low affinity site. The functional antagonism by MEN16132 (pA2 9.4) and Icatibant (pA2 9.1), towards BK (control EC50 6.1 nM) induced ileum contractions, was concentration-dependent and surmountable, but the Schild plot slope was less than unity.Conclusions and Implications:In mouse tissue, radiolabelled BK recognizes two binding sites and B2 receptor antagonists can compete only for the higher affinity one. The pharmacological profile of the novel non-peptide antagonist MEN16132 indicates that it exhibits subnanomolar affinity and potency for the mouse B2 receptor and is suitable for further characterization in in vivo pathophysiological models.British Journal of Pharmacology (2007) 150, 313–320. doi:10.1038/sj.bjp.0706995; published online 18 December 2006 [ABSTRACT FROM AUTHOR]

Background and Purpose:Although previous studies have demonstrated that neuropeptide Y (NPY) modulates nociceptors, the relative contributions of the Y1 and Y2 receptors are unknown. Therefore, we evaluated the effect of Y1 and Y2 receptor activation on nociceptors stimulated by bradykinin (BK) and prostaglandin E2 (PGE2).Experimental approach:Combined immunohistochemistry (IHC) with in situ hybridization (ISH) demonstrated that Y1- and Y2-receptors are collocated with bradykinin 2 (B2)-receptors in rat trigeminal ganglia (TG). The relative functions of the Y1 and Y2 receptors in modulating BK/PGE2-evoked CGRP release and increased intracellular calcium levels in cultured TG neurons were evaluated.Key results:The Y1 and Y2 receptors are co-expressed with B2 in TG neurons, suggesting the potential for direct NPY modulation of BK responses. Pretreatment with the Y1 agonist [Leu31,Pro34]-NPY, inhibited BK/PGE2-evoked CGRP release. Conversely, pretreatment with PYY(3-36), a Y2 agonist, increased BK/PGE2 evoked CGRP release. Treatment with NPY evoked an overall inhibitory effect, although of lesser magnitude. Similarly, [Leu31,Pro34]-NPY inhibited BK/PGE2-evoked increases in intracellular calcium levels whereas PYY(3-36) increased responses. NPY inhibition of BK/PGE2-evoked release of CGRP was reversed by the Y1 receptor antagonist, BIBO3304, and higher concentrations of BIBO3304 significantly facilitated CGRP release. The Y2 receptor antagonist, BIIE0246, enhanced the inhibitory NPY effects.Conclusions and implications:These results demonstrate that NPY modulation of peptidergic neurons is due to net activation of inhibitory Y1 and excitatory Y2 receptor systems. The relative expression or activity of these opposing receptor systems may mediate dynamic responses to injury and pain.British Journal of Pharmacology (2007) 150, 72–79. doi:10.1038/sj.bjp.0706967; published online 4 December 2006 [ABSTRACT FROM AUTHOR]

A conference paper on the role of extracellular products of the mastitis-inducing pathogens, Escherichia coli (EC), and Staphylococcus aureus (SA) in the activation of bovine milk kallikreins is presented. The study indicated that the presence in milk of the pathogens is associated with elevated bradykinin (BK) levels. It showed that both EC and SA directly activate BK formation in milk by activating synthetic tissue- and plasma-kallikreins-like activity in the milk.

A conference paper about the role of gap junctions in the bradykinin-induced relaxation of the bovine pulmonary supernumerary arteries is presented. It discusses on how the assessment was made with the use of fresh bovine lungs including the different phases the tissue underwent. Further, it revealed that gap junctions does not contribute to the bradykinin-induced relaxation of bovine supernumerary arteries instead it involved in the mediation with nitric acid.

We studied the modulation of pacemaker activities by bradykinin in cultured interstitial cells of Cajal (ICC) from murine small intestine with the whole-cell patch-clamp technique. Externally applied bradykinin produced membrane depolarization in the current-clamp mode and increased tonic inward pacemaker currents in the voltage-clamp mode.Pretreatment with bradykinin B1 antagonist did not block the bradykinin-induced effects on pacemaker currents. However, pretreatment with bradykinin B2 antagonist selectively blocked the bradykinin-induced effects. Also, only externally applied selective bradykinin B2 receptor agonist produced tonic inward pacemaker currents and ICC revealed a colocalization of the bradykinin B2 receptor and c-kit immunoreactivities, but bradykinin B1 receptors did not localize in ICC.External Na+-free solution abolished the generation of pacemaker currents and inhibited the bradykinin-induced tonic inward current. However, a Cl− channel blocker (DIDS) did not block the bradykinin-induced tonic inward current.The pretreatment with Ca2+-free solution and thapsigargin, a Ca2+-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the bradykinin-induced action.Chelerythrine and calphostin C, protein kinase C inhibitors or naproxen, an inhibitor of cyclooxygenase, did not block the bradykinin-induced effects on pacemaker currents.These results suggest that bradykinin modulates the pacemaker activities through bradykinin B2 receptor activation in ICC by external Ca2+ influx and internal Ca2+ release via protein kinase C- or cyclooxygenase-independent mechanism. Therefore, the ICC are targets for bradykinin and their interaction can affect intestinal motility.British Journal of Pharmacology (2006) 148, 918–926. doi:10.1038/sj.bjp.0706806; published online 19 June 2006 [ABSTRACT FROM AUTHOR]