S-nitrosocysteine elicits hemodynamic responses similar to those of the Bezold–Jarisch reflex via activation of stereoselective recognition sites

We report here that L-S-nitrosocysteine elicits rapid dose-dependent reductions in mean arterial blood pressure, heart rate, cardiac output and renal sympathetic nerve activity in conscious rats whereas D-S-nitrosocysteine elicits minor responses. The reductions in mean arterial blood pressure, heart rate and cardiac output elicited by L- and D-S-nitrosocysteine were markedly diminished after blockade of cardiac muscarinic cholinergic receptors whereas the reductions in renal sympathetic nerve activity were not affected. The Bezold-Jarisch reflex-like pattern of responses elicited by the stereoisomers, suggests that (i) L- and L-S-nitrosocysteine may activate stereoselective recognition sites on vagal cardiopulmonary afferents, which elicit hemodynamic responses via increases in cardiovagal efferent nerve activity and decreases in sympathetic nerve activity, and (ii) L-S-nitrosocysteine is a more potent agonist of these recognition sites than is D-S-nitrosocysteine.