Vasorelaxant Effects of the Bioflavonoid Chrysin in Isolated Rat Aorta

Abstract

Chrysin relaxed the contractions induced by noradrenaline in isolated endothelium-intact rat aortic rings (IC₅₀ = 16 ± 4 μM). Endothelium removal and N ^G-nitro-L-arginine methyl ester inhibited this relaxant effect. Chrysin potentiated the relaxation to acetylcholine under control conditions or after incubation with the superoxide anion generator hypoxanthine/xanthine oxidase. It also potentiated the relaxation induced by 3-morpholino-sydnonimine, sodium nitroprusside, and 8-bromoguanosine-3′:5′-cyclic-monophosphate. Therefore, vasorelaxation induced by chrysin in the rat aorta is endothelium- and NO-dependent. This effect is mediated by the prevention of O₂ ^--induced inactivation of endothelial derived NO and also by the potentiation of cGMP-induced vasodilatation.

Abbreviations

L-NAME:N ^G-nitro-L-arginine methyl ester

NO:nitric oxide

SIN-1:3-morpholino-sydnonimine

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