Relaxation induced by red wine polyphenolic compounds in rat pulmonary arteries: lack of inhibition by NO-synthase inhibitor

Some red wine polyphenols exert nitric oxide (NO)-dependent relaxation in systemic arteries, following activation of endothelial NO synthase (eNOS). In this study, the effect of red wine polyphenols was determined in rat intrapulmonary arteries, and the effect of some of these compounds was compared with the responses obtained in rat aorta. In pulmonary arteries, red wine polyphenolic extract (> 300 microg/mL) exerted relaxation that was not inhibited by the NOS inhibitor N(omega)-nitro-L-arginine methylester (L-NAME) or endothelium removal. Among the several fractions obtained from the extract, the one enriched with anthocyanins was less active than fractions containing non-anthocyanins. Among the latter, the most active for relaxing pulmonary arteries was the one enriched in the stilbene derivative trans-resveratrol (relaxation for concentration >10 microg/mL). Trans-piceid, the glucoside derivative of trans-resveratrol, was almost inactive. Trans-resveratrol-induced relaxation, as well as relaxation to the anthocyanin delphinidin, was L-NAME-insensitive in pulmonary arteries. In aorta, trans-resveratrol and trans-piceid exerted similar effects to those in pulmonary arteries that were also not inhibited by L-NAME. However, red wine polyphenolic extract and delphinidin induced relaxation of aorta at much lower concentrations (about 10 microg/mL) than in pulmonary arteries, and their effects were inhibited by L-NAME. These data show differences between small intrapulmonary arteries and systemic conductance arteries in their responses to red wine polyphenols, the major difference being that the relaxant effect of these compounds is not blunted by NOS inhibitor in pulmonary arteries. They suggest that red wine polyphenols act directly on smooth muscle to promote pulmonary artery relaxation.     

Non-invasive measurement of the haemodynamic effects of inhaled salbutamol, intravenous L-arginine and sublingual nitroglycerin

AIMS

To examine the effects of salbutamol and L-arginine, two compounds acting largely on the endothelium, and the endothelium-independent agent nitroglycerin on blood pressure, arterial compliance, cardiac function and vascular resistance.

METHODS

Continuous radial pulse wave analysis, whole-body impedance cardiography, and plethysmographic blood pressure from fingers in the supine position and during head-up tilt were recorded in nine healthy subjects. Data were captured before and after L-arginine (10 mg mg⁻¹ min⁻¹) or saline infusion, salbutamol (400 µg) or placebo inhalation, and sublingual nitroglycerin (0.25 mg) or placebo resoriblet.

RESULTS

The results of all measurements were comparable before drug administration. The effects of inhaled salbutamol were apparent in the supine position: systemic vascular resistance (−9.2 ± 2.6%) and augmentation index (−4.0 ± 1.5%) decreased, and heart rate (8.6 ± 2.5%) and cardiac output (8.8 ± 3.1%) increased. L-arginine had no clear effects on supine haemodynamics, but during head-up tilt blood pressure was moderately decreased and reduction in aortic reflection time prevented, indicating improved large arterial compliance. Nitroglycerin reduced supine vascular resistance (−6.7 ± 1.8%) and augmentation index (−7.4 ± 1.6%), and increased cardiac output (+9.2 ± 2.7%). During head-up tilt, nitroglycerin increased cardiac output (+10.6 ± 5.6%) and heart rate (+40 ± 7.5%), decreased vascular resistance (−7.8 ± 5.8%) and augmentation index (−18.7 ± 3.2%), and prevented the decrease in aortic reflection time.

CONCLUSIONS

Inhaled salbutamol predominantly changed supine haemodynamics, whereas the moderate effects of L-arginine were observed during the head-up tilt. In contrast, small doses of nitroglycerin induced major changes in haemodynamics both supine and during the head-up tilt. Altogether, these results emphasize the importance of haemodynamic measurements in both the supine and upright positions.     

Hydrogen sulfide mediates the vasoactivity of garlic

The consumption of garlic is inversely correlated with the progression of cardiovascular disease, although the responsible mechanisms remain unclear. Here we show that human RBCs convert garlic-derived organic polysulfides into hydrogen sulfide (H(2)S), an endogenous cardioprotective vascular cell signaling molecule. This H(2)S production, measured in real time by a novel polarographic H(2)S sensor, is supported by glucose-maintained cytosolic glutathione levels and is to a large extent reliant on reduced thiols in or on the RBC membrane. H(2)S production from organic polysulfides is facilitated by allyl substituents and by increasing numbers of tethering sulfur atoms. Allyl-substituted polysulfides undergo nucleophilic substitution at the alpha carbon of the allyl substituent, thereby forming a hydropolysulfide (RS(n)H), a key intermediate during the formation of H(2)S. Organic polysulfides (R-S(n)-R'; n > 2) also undergo nucleophilic substitution at a sulfur atom, yielding RS(n)H and H(2)S. Intact aorta rings, under physiologically relevant oxygen levels, also metabolize garlic-derived organic polysulfides to liberate H(2)S. The vasoactivity of garlic compounds is synchronous with H(2)S production, and their potency to mediate relaxation increases with H(2)S yield, strongly supporting our hypothesis that H(2)S mediates the vasoactivity of garlic. Our results also suggest that the capacity to produce H(2)S can be used to standardize garlic dietary supplements.     

Activation of sphingosine kinase by muscarinic receptors enhances NO-mediated and attenuates EDHF-mediated vasorelaxation

Local formation of the sphingomyelin metabolite sphingosine-1-phosphate (S1P) within the vascular wall has been shown to modulate vascular reactivity. In this study we investigated whether sphingosine kinase, the enzyme responsible for S1P synthesis, plays a role in muscarinic receptor-mediated NO production and vascular relaxation in different blood vessel types. For this purpose, sphingosine kinase translocation and sphingolipid-dependent NO-production after muscarinic receptor stimulation were assessed in an endothelial cell line. Furthermore, we used the sphingosine kinase inhibitor N,N-dimethylsphingosine (DMS) to investigate the role of sphingosine kinase in the relaxant responses to the muscarinic agonist methacholine (MCh) in isolated rat aorta and mesenteric arteries. Activation of M₃-receptors in an endothelial cell line induced a fast translocation of YFP-tagged sphingosine kinase-1 from the cytosol to the plasma membrane. Concomitant NO-production in this cell line was partially inhibited by DMS. Accordingly, in rat aorta the relaxant responses to MCh were attenuated in the presence of DMS, while the responses to the NO-donor sodium nitroprusside were unaltered. In contrast, DMS enhanced the relaxant responses to MCh in mesenteric artery preparations. This effect could also be observed in the presence of NO synthase and cyclooxygenase inhibitors, indicating that sphingosine kinase inhibition specifically enhanced endothelium-derived hyperpolarizing factor-mediated (i.e. non-NO and non-prostacyclin-dependent) relaxation. We conclude that sphingosine kinase differentially regulates vascular tone in different vessel types, enhancing NO-dependent vasorelaxation but counteracting EDHF-dependent vasorelaxation. This observation enhances our understanding of the complex mechanisms by which sphingolipids regulate vascular homeostasis. Moreover, a disturbed regulation of sphingolipid metabolism in the vascular wall may therefore play a role in the aetiology/pathology of disease states characterized by endothelial dysfunction. Returned for 1. Revision: 29 January 2008 1. Revision received: 23 May 2008 Returned for 2. Revision: 25 June 2008 2. Revision received: 7 July 2008 Returned for 3. Revision: 23 July 2008 3. Revision received: 28 July 2008     

激活瞬时受体电位香草醛亚家族1抑制RhoA/Rho激酶改善高脂介导的血管舒张功能异常

目的 探讨膳食辣椒素通过激活瞬时受体电位香草醛亚家族1(TRPV1)对高脂饮食介导的血管功能障碍的作用及机制.方法 10周龄雄性C57 BL/6J小鼠,分别给予普通饮食(普通饲料)、普通饮食+辣椒素(普食+0.01％辣椒素)、高脂饮食(高脂饲料)、高脂饮食+辣椒素(高脂饲料+0.01％辣椒素)干预,20周后观察鼠尾血压...     

Remifentanil-induced mechanical responses and membrane potential changes in human umbilical arteries

BACKGROUND: The aim of this study was to evaluate the characteristic features of the mechanical responses and membrane potential changes induced by remifentanil in human umbilical arteries (HUAs). The ionic mechanisms underlying the electrophysiological responses were pharmacologically assessed using two K(+) channel blockers. METHODS: Thirty-eight HUAs were obtained. Contraction-relaxation, membrane potential changes and electrical responses of the HUAs were recorded. RESULTS: Remifentanil produced concentration-dependent relaxation in both endothelium-intact and endothelium-denuded HUA rings. Remifentanil produced a significantly greater relaxation response in intact than in denuded HUA rings. In endothelium-intact rings, pre-treatment with L-nitroarginine [N(w)-NITRO-(L)-ARGININE (L-NO-ARG)] or indomethacin decreased the degree of remifentanil-induced relaxation. Remifentanil (10(-9)-10(-6) mol/l) produced a transient concentration-dependent membrane hyperpolarization, which was not decreased by pre-treatment with L-NO-ARG or indomethacin. It also produced a small concentration-dependent hyperpolarization in the presence of charybdotoxin or tetraethylammonium. CONCLUSION: In both endothelium-intact and endothelium-denuded HUAs, remifentanil induces concentration-dependent vasorelaxation and simultaneously releases nitric oxide, prostaglandins and possibly an endothelium-derived hyperpolarizing factor. In addition, it produces hyperpolarization in a dose-dependent manner. Hyperpolarization induced by remifentanil involves the activation of Ca(2+)-dependent and Ca(2+)-independent potassium channels regulated by intracellular Ca(2+).     

Effect of ropivacaine on endothelium-dependent phenylephrine-induced contraction in guinea pig aorta

BACKGROUND: Previous studies have shown that ropivacaine has biphasic vascular effects, causing vasoconstriction at low concentrations and vasorelaxation at high concentrations. This study was designed to examine the role of the endothelium during accidental intravascular absorption of ropivacaine, and to elucidate the mechanisms responsible. METHODS: Isolated guinea pig aortic rings were suspended for isometric tension recording. The effects of ropivacaine on endothelium-intact and endothelium-denuded aortic rings were assessed. Endothelium-intact aortic rings were pre-contracted with phenylephrine before being exposed to ropivacaine and acetylcholine, in order to generate and compare concentration-response curves. In the absence and presence of yohimbine, propranolol, atropine, indometacin, N(G)-nitro-l-arginine methyl ester (l-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or methylene blue, the contractile response induced by ropivacaine was assessed on endothelium-intact aortic rings pre-contracted with phenylephrine. RESULTS: Ropivacaine (3 x 10(-4) to 10(-2) mol/l) produced vasoconstriction in endothelium-denuded aortic rings, whereas no such response was observed in aortic rings with intact endothelium. In phenylephrine pre-contracted intact aortic rings, ropivacaine induced a greater degree of vasorelaxation than did acetylcholine. Yohimbine, propranolol and atropine all failed to affect the relaxation responses induced by ropivacaine. However, pre-treatment with indometacin (cyclo-oxygenase inhibitor), l-NAME (nitric oxide synthase inhibitor), methylene blue (soluble guanylyl cyclase inhibitor) or ODQ (soluble guanylyl cyclase inhibitor), significantly decreased the ropivacaine-induced relaxation of endothelium-intact aortic rings (3 x 10(-4) to 10(-2) mol/l). CONCLUSIONS: Ropivacaine elicits an endothelium-dependent vasorelaxation in phenylephrine pre-contracted aortic rings via the nitric oxide-cyclic guanosine 3',5'-monophosphate pathway and the prostaglandin system.     

Cardiovascular effects of a novel potent and highly selective azaindole-based inhibitor of Rho-kinase

BACKGROUND AND PURPOSE: Rho-kinase (ROCK) has been implicated in the pathophysiology of altered vasoregulation leading to hypertension. Here we describe the pharmacological characterization of a potent, highly selective and orally active ROCK inhibitor, the derivative of a class of azaindoles, azaindole 1 (6-chloro-N4-{3,5-difluoro-4-[(3-methyl-1H-pyrrolo[2,3-b]pyridin-4-yl)oxy]-phenyl}pyrimidine-2,4-diamine). EXPERIMENTAL APPROACH: Pharmacological characterization of azaindole 1 was performed with human recombinant ROCK in vitro. Vasodilator activity was determined using isolated vessels in vitro and different animal models in vivo. KEY RESULTS: This compound inhibited the ROCK-1 and ROCK-2 isoenzymes with IC50 s of 0.6 and 1.1 nM in an ATP-competitive manner. Although ATP-competitive, azaindole 1 was inactive against 89 kinases (IC50>10 microM) and showed only weak activity against an additional 21 different kinases (IC50=1-10 microM). Only the kinases TRK und FLT3 were inhibited by azaindole 1 in the sub-micromolar range, albeit with IC50 values of 252 and 303 nM, respectively. In vivo, azaindole 1 lowered blood pressure dose-dependently after i.v. administration in anaesthetized normotensive rats. In conscious normotensive and spontaneously hypertensive rats azaindole 1 induced a dose-dependent decrease in blood pressure after oral administration without inducing a significant reflex increase in heart rate. In anaesthetized dogs, azaindole 1 induced vasodilatation with a moderately elevated heart rate. CONCLUSIONS AND IMPLICATIONS: Azaindole 1 is representative of a new class of selective and potent ROCK inhibitors and is a valuable tool for the elucidation of the role of ROCK in the cardiovascular system.     

Vasorelaxant effect of stilbenes from rhizome extract of rhubarb (Rheum undulatum) on the contractility of rat aorta

The vascular relaxant effect of the rhizome extract of Rheum undulatum was evaluated with isolated rat thoracic aorta preparations. The methanol extract of the rhizome induced a concentration-dependent relaxation of aortic preparations precontracted with 0.3 microm phenylephrine (EC50 value: 5.8 microg/mL). The activity-guided fractionation of the extract led to the isolation of seven hydroxystilbene components as active principles, i.e. piceatannol, resveratrol, desoxyrhapontigenin, rhapontigenin, piceid, rhaponticin and epsilon-viniferin. Of these, piceatannol, a tetrahydroxystilbene, exhibited the most potent vascular relaxant effect in rat aortic preparations (EC50 value 2.4 microm). The vasorelaxant effect of piceatannol on endothelium-intact aorta rings was diminished completely by the removal of functional endothelium or by pretreatment of the aortic tissues with N(G)-nitro-l-arginine methyl ester. These results suggest that piceatannol may be the major mediator responsible for the vasorelaxing properties of the rhizome extract of Rheum undulatum and the vasorelaxant effects of the piceatannol may be mediated via endothelium-dependent nitric oxide signaling pathway.