Relaxant effects of phytoestrogen and estrogen on Canine Coronary Arteries in Vitro

ObjectiveTo study the vasorelaxant effect of resveratrol （RST） on coronary artery as compared with 17 β-estradiol（EST）.Methods Canine coronary rings were prepared and mounted in the organ bath, after an equilibration period.ResultsSimilarly to EST, RST dose-dependently attenuate 50 mmol/L KCl elicited-contraction in canine coronary rings with IC 50 values of 68.3±18.3 and 22.6±8.5 μmol/L respectively.The relaxant extent by both estrogens was decreased 15%-25% after the incubation with the inhibitor of nitric oxide synthase N ω-L-nitro-arginine （L-NNA）, sodium orthovanadate （SOV） and endothelium removal （P＜0.01） .However, after exposure to Propranolol （PROP）, the transcription inhibitor Actinomycin D （ACD） or the oestrogen receptor antagonist Tamoxifen （TAM）, no changes in vaso-relaxant effect induced by both estrogens have been found.Conclusion The vasorelaxant effect of RST and EST was endothelium-dependent and partially related to NO synthesis.However, the relaxations induced by RST and EST in isolated coronary rings were not related to adrenergic β receptor, conventional estrogen receptor as well as the classic genomic pathway.