Endothelial Nitric Oxide Synthase in Vascular Disease

Nitric oxide (NO*) is an important protective molecule in the vasculature, and endothelial NO* synthase (eNOS) is responsible for most of the vascular NO* produced. A functional eNOS oxidizes its substrate L-arginine to L-citrulline and NO*. This normal function of eNOS requires dimerization of the enzyme, the presence of the substrate L-arginine, and the essential cofactor (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4), one of the most potent naturally occurring reducing agents. Cardiovascular risk factors such as hypertension, hypercholesterolemia, diabetes mellitus, or chronic smoking stimulate the production of reactive oxygen species in the vascular wall. Nicotinamide adenine dinucleotide phosphate (NADPH)…