ENDOTHELIUM-DEPENDENT VASORELAXING ACTIVITY OF WINE AND OTHER GRAPE PRODUCTS

Current interest in the presumed benefits of wine in protecting agains t coronary heart disease prompted us to investigate possible effects o f various grape products on vascular function in vitro. Certain wines, grape juices, and grape skin extracts relaxed precontracted smooth mu scle of intact rat aortic rings but had no effect on aortas in which t he endothelium had been removed. Quercitin and tannic acid, compounds known to be present in grape skins, also produced endothelium-dependen t relaxation; two other grape skin compounds, resveratrol and malvidin , did not relax the rings. Phenylephrine-induced contractions were att enuated by prior exposure of aortic rings to grape skin extracts. The extracts also increased guanosine 3',5'-cyclic monophosphate (cGMP) le vels in intact vascular tissue, and both relaxation and the increase i n cGMP were reversed by N(G)-monomethyl-L-arginine and N(G)-nitro-L-ar ginine, competitive inhibitors of the synthesis of the endothelium-der ived relaxing factor, nitric oxide (NO). The vasorelaxation induced by grape products therefore appears to be mediated by the NO-cGMP pathwa y. If such responses occur in vivo, they could conceivably help to mai ntain a patent coronary artery and thereby possibly contribute to a re duced incidence of coronary heart disease.