Effects of red wine, alcohol, and quercetin on coronary resistance and conductance arteries

Moderate consumption of alcoholic beverages is associated with a reduced ri sk of coronary heart disease (CHD). Some evidence suggests that red wine is particularly beneficial in this regard and may account in part for the Fre nch paradox, although the mechanism of this effect is unknown. We assessed the effects of red wine, ethanol, and quercetin, a major flavonoid constitu ent of red wine, in coronary resistance vessels (80-150 mum, i.d.) and cond uctance vessels (300-525 mum, i.d.) of the rabbit. Vessel wall tension was measured in isolated segments maintained in a wire-type myograph (37 degree sC) and preconstricted with 30 mM K+. At an alcohol concentration (14 mM) e quivalent to moderate consumption, red wine evoked a small, transient const rictor effect in resistance and conductance vessels (9 +/- 4%, n = 5; 8 +/- 1%, n = 7, respectively; p < 0.05). Ethanol alone at this concentration wa s without effect. Quercetin (5.6, 8, and 30 <mu>M) significantly relaxed re sistance (-32 +/- 4%, n = 10; -47 +/- 2%, n = 7; -82 +/- 6%, n = 8, respect ively) and conductance (-20 +/- 3%, n = 8; -32 +/- 4%, n = 8; -72 +/- 7%, n = 8, respectively) coronary arteries. Vasorelaxation by quercetin was endo thelium-independent and was significantly greater in resistance than in con ductance vessels. These data suggest that red wine and ethanol do not evoke relaxation in small coronary arteries at concentrations associated with mo derate consumption. Quercetin elicits marked coronary vasorelaxation that i s endothelium-independent. However, the concentrations of quercetin necessa ry to achieve this action are not attained with moderate red wine consumpti on.