Abstract:

Under the catalysis of dioxygenase L-arginine is converted to L-citrulline and nitric oxide, the latter exhibits endothelium derived relaxing factor(EDRF)-like actions.N^G-nitro-L-arginine has an inhibitory effect on the biosynthesis of EDRF in vitro and in vivo, hence it is an EDRF antagonist.The results of the present work indicate that both N^G-NO2-L-Arg-OH and HCl·N^G-NO2-L-Arg-OCH3 have vasodilating effect in vitro, but produced dose-depending increase in mean arterial blood pressure (MAP) in vivo.In vitro HCl·N^G-NO2-L-Arg-N^G-NO2-L-Arg-OCH3 relaxed rat aortic strip pretreated with noradrenaline(NE).In vivo, however, it produced biphasic effect, i.e, decreased MAP at lower dose and increases MAP at higher dose, N^G-Tos-L-Arg-N^G-Tos-L-Arg-OH produced dose-depending vasodilating and hypotensive actions.

Key words: Vasoactive, Protected L-arginine, EDRF-like functions