L-NG-Monomethylarginine, Acetate Salt (L-NMMA), is an analogue of L-arginine that has been shown to inhibit Ca2+-dependent NOS3 (endothelial NOS) from porcine aorta. In an experiment on porcine aortic rings, L-NMMA was shown to cause contraction and inhibition of the endothelium-dependent relaxation induced by acetylcholine. This compound has also been noted to elicit a dose-dependent increase in mean systemic arterial blood pressure accompanied by bradycardia. Experiments on cat vascular endothelia show that L-NMMA can increase leukocyte adherence and emigration and reduce venular shear rate. Low shear rates have been shown to promote platelet-endothelial and leukocyte-endothelial cell adhesion in mesenteric venules. L-NG-Monomethylarginine, Acetate Salt (L-NMMA) is an inhibitor of NOS1 and NOS2. An L-arginine analogue inhibitor of Ca2+-dependent NOS3 (endothelial NOS)