In vivo evidence that l- S-nitrosocysteine may exert its vasodilator effects by interaction with thiol residues in the vasculature

Abstract

This study examined the effects of the lipophobic thiol chelator, para-hydroxymercurobenzoic acid (25 and 50 μmol/kg, i.v.) on the falls in mean arterial blood pressure and regional vascular resistances produced by l- S-nitrosocysteine (400 nmol/kg, i.v.) and the nitric oxide (NO)-donors, ( Z)-1-| N-methyl- N-[6( N-methylammoniohexyl)amino]|diazen-1-ium-1,2-diolate (MAHMA NONOate, 25 nmol/kg, i.v.) and sodium nitroprusside (10 μg/kg, i.v.), in urethane-anesthetized rats. The l- S-nitrosocysteine-induced responses were markedly diminished whereas the MAHMA NONOate- and sodium nitroprusside-induced responses were minimally affected by para-hydroxymercurobenzoic acid. These results suggest that the vasodilator actions of l- S-nitrosocysteine involves the interaction with membrane thiols in vascular smooth muscle of resistance arteries and that para-hydroxymercurobenzoic acid does not markedly affect NO-mediated vasodilation.