Chrysin relaxed the contractions induced by noradrenaline in isolated endot
helium-intact rat aortic rings (IC50 = 16 +/- 4 muM). Endothelium removal a
nd Nc-nitro-L-arginine methyl ester inhibited this relaxant effect. Chrysin
potentiated the relaxation to acetylcholine under control conditions or af
ter incubation with the superoxide anion generator hypoxanthine/xanthine ox
idase. It also potentiated the relaxation induced by 3-morpholino-sydnonimi
ne, sodium nitroprusside, and 8-bromoguanosine-3 ' :5 '- cyclic-monophospha
te. Therefore, vasorelaxation induced by chrysin in the rat aorta is endoth
elium- and NO-dependent. This effect is mediated by the prevention of O-2(-
)-induced inactivation of endothelial derived NO and also by the potentiati
on of cGMP-induced vasodilatation.