Neuronal Nitric Oxide Synthase Is Expressed in Rat Vascular Smooth Muscle Cells

Abstract—The nitric oxide synthase (NOS) inhibitor nitro- L-arginine augmented,the contractions to angiotensin (Ang) II in carotid artery rings without endothelium,from,spontaneously,hypertensive,rats (SHR) but not normotensive Wistar-Kyoto rats, suggesting the possibility of nonendothelial NOS activity in SHR arteries. In SHR artery without endothelium, the potentiation of Ang II contraction by nitro- L-arginine was prevented by L-arginine, but not by D-arginine, and was observed also in the presence of oxyhemoglobin, monomethyl-L-arginine, and 7-nitroindazole, but not in the presence of aminoguanidine. In further support of NOS activation by Ang II in nonendothelial cells, Ang II but not acetylcholine stimulated cGMP levels by 2-fold in SHR arteries without endothelium; nitro-L-arginine decreased both basal and Ang II‐stimulated cGMP levels. When NOS activity in SHR arteries was measured, no calcium-