EFFECT OF RED WINE ON ENDOTHELIUM-DEPENDENT RELAXATION IN RABBITS

1, Published data on the effects of red wine, ethanol and flavonoids o n endothelium-dependent relaxation are equivocal, The present study wa s undertaken to determine the effects of red wine, ethanol and selecte d flavonoids present in red wine on endothelium-dependent relaxation. 2, Aortic rings from New Zealand White rabbits were set up in organ ba ths (20 mi) and contracted with noradrenaline (10(-6) mol/l), An attem pt was made to elicit dose-dependent relaxant responses to red wine (1 5, 30, 40, 80 or 120 mu l), ethanol (5.4, 10.8 and 16.2 mu l) and the flavonoids catechin, epicatechin, quercetin and polymeric phenols (10( -7) to 10(-4) mol/l), In some experiments, endothelium-dependent relax ation to cumulative doses of acetylcholine (10(-9) to 10(-6) mol/l) wa s determined before and after incubating the rings for 15 min with red wine (120 mu l), ethanol (16.2 mu l), quercetin (10(-5) mol/m) catech in (10(-5) mol/l) epicatechin (10(-5)mol/l) and PPs (10(-5) mol/l) res pectively, cGMP was also measured in some rings in the control state a nd after addition of 120 pi of red wine, sodium nitroprusside (10(-4) mol/l) and polymeric phenols (10(-5) mol/l), 3, Red wine evoked a dose -dependent relaxation in aortic rings, The highest volumes of wine (12 0 mu l) relaxed the vessels by 71.35 +/- 7.89% of the maximal contract ion (8.95 +/- 0.97 g), Polymeric phenols also relaxed the precontracte d rings, These responses were abolished by N-G-L-argine methyl ester ( L-NAME) and by removal of endothelium, Addition of red wine, polymeric phenols and sodium nitroprusside increased the cGMP content of the ri ngs, In tissues previously incubated with red wine and polymeric pheno ls, endothelium-dependent relaxation in response to acetylcholine was attenuated, Ethanol had no such effect,4, Acute exposure of aortic rin gs to red wine and polymeric phenols evokes an endothelium-dependent r elaxation which is mediated by nitric oxide, However, prior exposure t o both red wine and polymeric phenols has a second effect in that it a ttenuates the endothelium-dependent relaxation evoked by acetylcholine , Since this effect is restored by arginine, it is likely to be due to depletion of substrate for nitric oxide synthase.