Evidence that different mechanisms underlie smooth muscle relaxation to nitric oxide and nitric oxide donors in the rabbit isolated carotid artery

摘要

The endothelium-dependent relaxants acetylcholine (ACh; 0.03-10μM0 and A23187(0.03-10μM), and nitric oxide (NO), applied either as authentic NO(0.01-10μM) or as the NO donors 3-morpholino- sydnonimine(SIN-1; 0.1-10μM) and S-nitroso-N-acetylpenicillamine(SNAP; 0.1-10μM), each evoked concentration-dependent relaxation in phenylephrine stimulated (1-3μM; mean contraction and depolarization, 45.8±5.3 mV and 31.5±3.3 mN; n = 10)segments of rabbit isolated carotid artery. In each case, relaxation closely correlated with repolarization of the smooth muscle membrane potential and stimulated a maximal reversal of around 95/100 and 98/100 of the phenylephrine-induced depolarization and contraction, respectively.