A pro-drug of L- NG-Nitro-L-arginine (L-NOARG). Hydrolysis of the methyl ester of L-NAME by cellular esterases converts it into a fully functional L-NOARG that exhibits some selectivity for inhibition of neuronal and endothelial NOS isoforms (Ki values of 15 nM, 39 nM, and 4.4 µM for nNOS (bovine), eNOS (human), and iNOS (mouse), respectively). L-NAME inhibits cGMP formation in endothelial cells with an IC₅₀ of 3.1 µM (in the presence of 30 µM arginine) and reverses the vasodilation effects of acetylcholine in rat aorta rings with an EC₅₀ of 0.54 µM.