nitric oxide 1

nitric oxide (NO)¹,

a colorless gas and stable free radical commonly found in tissues of humans and other mammals. It is also prepared commercially by passing air through an electric arc. Biologically the effector molecule is commonly synthesized from the amino acid arginine. NO participates in many biologic functions, such as neurotransmission, vasodilation, cytotoxicity of macrophages, lipid-lowering therapy, and inhibition of platelet aggregation. NO is involved in smooth muscle action and penile erection. It may improve oxygenation in patients with high-altitude pulmonary edema. NO deprivation may lead to high blood pressure and the formation of atherosclerotic plaque. On contact with air, NO is quickly converted to the very poisonous nitrogen dioxide (NO₂).