NG-amino-L-arginine: a new potent antagonist of L-arginine-mediated endothelium-dependent relaxation.

This study examined the influence of NG-amino-L-arginine, a novel structural analog of L-arginine, on endothelium-dependent relaxation, contraction, and cyclic GMP accumulation in isolated rings of bovine pulmonary artery. NG-Amino-L-arginine caused potent and stereoselective endothelium-dependent contraction that was associated with a marked and endothelium-dependent decline in basal levels of cyclic GMP in smooth muscle. NG-Amino-L-arginine caused concentration-dependent, competitive, and stereoselective antagonism of acetylcholine-elicited relaxation and cyclic GMP accumulation. NG-Amino-L-arginine was 100- to 300- fold more potent than NG-methyl-L-arginine and did not inhibit endothelium-independent relaxation elicited by nitroglycerin. This potent inhibitory analog of L-arginine should be a useful chemical probe for studying the biosynthesis and biological role of L-arginine-derived nitric oxide both in vitro and in vivo.