Redox regulation of S-nitrosocysteine-mediated vasodilation in vivo

This study examined the effects of the lipophobic electron acceptor, nitrob lue tetrazolium (2 x 5 mu mol/kg, i.v.) on the vasodilation produced by the putative endothelium-derived 5-nitrosothiol, L-S-nitrosocysteine (400 nmol /kg, i.v.), and the nitric oxide (NO) donor, (Z)-1-/N-methyl-N-[6( N-methyl ammoniohexyl)amino]/diazen-1-ium-1,2-diolate (MAHMA NONOate, 25 nmol/kg, i. v.), in anesthetized rats. The administration of nitroblue tetrazolium resu lted in delayed but long-lasting increases in vascular resistances. The L-S -nitrosocysteine-induced vasodilator responses were markedly diminished whe reas the MAHMA NONOate-induced responses were not affected by nitroblue tet razolium. These results support the possibility that L-S-nitrosocysteine in teracts with membrane thiols that are subject to nitroblue tetrazolium-indu ced oxidation (i.e., disulfide-bridge formation) and that nitroblue tetrazo lium-induced vasoconstriction may involve a loss of potency of endothelium- derived S-nitrosothiols. (C) 2000 Elsevier Science B.V. All rights reserved .