The mechanisms of peroxynitrite-induced relaxations in isolated rat anococcygeus muscle

We have previously reported that peroxynitrite (ONOO-) caused relaxations on isolated rat anococcygeus muscle and in the present study the possible mechanisms of the relaxant effect were investigated. ONOO- (0.03-1.0 mmol/l)-induced relaxations were reduced significantly by the presence of an ATP-sensitive potassium channel (K-ATP(+) channel) blocker, glibenclamide (0.3 mumol/1), or 1H-(1,2,4)oxadiazolo(4,3-alpha)quinoxalin-1-one (ODQ) (30.0 mumol/l), a guanylyl cyclase inhibitor. However, 3-aminobenzamide (3.0 mmol/l), an inhibitor of poly(ADP-ribose)synthase, did not influence the relaxant effect of ONOO- (1.0 mmol/l). Results of the present study implicate that activation of K-ATP(+) channels and/or cGMP/K-ATP(+) channel interaction might play a role in the relaxant responses to ONOO- in isolated rat anococcygeus muscle Copyright (C) 2002 S. KargerAG, Basel.