Nitric oxide production and endothelium‐dependent vasorelaxation induced by wine polyphenols in rat aorta

Abstract

1 The aim of this work was to investigate the mechanism of vasorelaxation induced by red wine polyphenolic compounds (RWPC) and two de®ned polyphenols contained in wine, leucocyanidol and catechin. The role of the endothelium, especially endothelium-derived nitric oxide (NO), was also investigated. 2 Relaxation produced by polyphenols was studied in rat aortic rings with and without functional endothelium, pre-contracted to the same extent with noradrenaline (0.3 and 0.1 mM, respectively). RWPC and leucocyanidol, but not catechin, produced complete relaxation of vessels with and without endothelium. However, 1000 fold higher concentrations were needed to relax endothelium-denuded rings compared to those with functional endothelium. 3 High concentrations of catechin (in the range of 10 71 g l 71 ) only produced partial relaxation (maximum 30%) and had the same potency in rings with and without endothelium. 4 The NO synthase inhibitor, N o -nitro-L-arginine-methyl-ester (L-NAME, 300 mM) completely abolished the endothelium-dependent but not the endothelium-independent relaxations produced by all of the polyphenolic compounds. 5 In contrast to superoxide dismutase (SOD, 100 u ml 71 ), neither RWPC nor leucocyanidol a ected the concentration-response curve for the NO donor, SIN-1 (3-morpholino-sydnonimine) which also produces superoxide anion (O 2 7 ). 6 In aortic rings with endothelium, RWPC (10 72 g l 71 ) produced a 7 fold increase in the basal production of guanosine 3' : 5'-cyclic monophosphate (cyclic GMP) which was prevented by L-NAME (300 mM). 7 Electron paramagnetic resonance (e.p.r.) spectroscopy studies with Fe 2+ -diethyldithiocarbamate as an NO spin trap demonstrated that RWPC and leucocyanidol increased NO levels in rat thoracic aorta about 2 fold. This NO production was entirely dependent on the presence of the endothelium and was abolished by L-NAME (300 mM). 8 These results show that RWPC and leucocyanidol, but not the structurally closely related polyphenol catechin, induced endothelium-dependent relaxation in the rat aorta. They indicate that this e ect results from enhanced synthesis of NO rather than enhanced biological activity of NO or protection against breakdown by O 2 7 . It is concluded that some polyphenols, with speci®c structure, contained in wine possess potent endothelium-dependent vasorelaxing activity.

Grape products and cardiovascular disease risk factors

“…In an ex-vivo experiment with aortic rings from rats incubated with red grape polyphenols, there was a two-fold increase in the NO-Fe(diethyldithiocarbamate) 2 electron paramagnetic resonance, which indicates the generation of NO; this NO production was completely prevented by the NO synthase inhibitor L-NAME (49) . Similarly, after supplementing rats with red wine and observing an anti-thrombotic effect (50) , the effects produced by red wine were prevented by L-NAME, indicating the involvement of NO in this process.…”

Wine polyphenols induce hypotension, and decrease cardiac reactivity and infarct size in rats: involvement of nitric oxide

“…Four groups of male Wistar rats (12-14 week old) were used and treated daily for 7 days by intra-gastric gavage: the first group (control) received the vehicle containing 5% glucose, the second group received RWPC (20 mg kg À1 day À1 ), the third group received L-NAME (2 mg kg À1 day À1 ), a dose at which it had no effect on blood pressure per se, and the fourth group was given a combination of RWPC plus L-NAME. This dose of RWPC has been previously shown to induce cardiovascular effects (Diebolt et al, 2001) and it corresponds to 10 times the concentration that produced maximal relaxation of rat aortic rings in vitro (Andriambeloson et al, 1997;1999). As only 5-10% of polyphenols can be absorbed in the digestive tract (Duthie et al, 1998), it may be assumed that the concentration of polyphenols present in the plasma is comparable to the concentration at which RWPC produced endothelium-dependent relaxation in rat aorta.…”

“…An increase in NO production has been reported to be induced by RWPC in vitro in cultured endothelial cells , in rat aortic rings with endothelium (Andriambeloson et al, 1997;1999) and in vivo either in human beings or rats (Wollny et al, 1999;Matsuo et al, 2001). In the present study, evidence is provided that, at a dose at which it had no effect on blood pressure per se, L-NAME treatment completely prevented the hypotensive effect of RWPC, the increase of nitrite production of the heart both under basal and in response to carbachol in RWPC-treated heart.…”

“…of each monomeric form of catechin and epicatechin), 64 mg g À1 of total anthocyanins (including 36% of malvidin-3-glucoside), 5 mg g À1 of total flavonols and 8.7 mg g À1 of total phenolic acids (including 19.5% of caftaric acid) as previously described (Andriambeloson et al, 1997). The vehicle used for the administration of RWPC and L-NAME was 5% glucose.…”

“…Moreover, we reported recently that RWPC accelerated the regression of blood pressure and improved structural and functional cardiovascular changes including cardiac fibrosis in hypertensive rats (Bernatova et al, 2002). These effects of RWPC probably involved the NO pathway; in as much as enhanced in vitro endothelium-dependent relaxation was observed as a result of enhanced NO synthesis (Andriambeloson et al, 1997;1999). Experimental studies on the cardiac effects of RWPC have essentially focused on their acute effects against ischaemia/reperfusion injury.…”