VASORELAXING ACTIVITY OF RESVERATROL AND QUERCETIN IN ISOLATED RAT AORTA

1. Both resveratrol and quercetin dose-dependently inhibited the contr actile response to noradrenaline (NA) in isolated endothelium-intact r at aorta. This inhibitory effect on vascular contraction was blocked b y pretreatment of the blood vessel with the nitric oxide (NO) synthase inhibitor, L-NNA (1 mu M). 2. Quercetin at a concentration >1 x 10(-5 ) M, and resveratrol at >3 x 10(-5) M, caused relaxation of the phenyl ephrine (PE) precontracted endothelium-intact aorta, and L-NNA, at 1 x 10(-6) M, reversed the relaxation. 3. At higher concentrations, >6 x 10(-5) M, resveratrol and quercetin also relaxed the endothelium-denud ed aortic rings, However, this effect could not be reversed by the NO inhibitor. 4. It is concluded that resveratrol and quercetin exert bot h indirect and direct vasodilator effects on the blood vessel by nitri c oxide-mediated and non-NO-mediated mechanisms, respectively.