ABSTRACT
Nitric oxide (NO) is synthesized by nitric oxide synthase (NOS) through a complex set of redox reactions involving molecular oxygen and l-arginine as substrates, NADPH as electron donor, and avin-adenine dinucleotide, avin mononucleotide, tetrahydrobiopterin (BH4), heme, and calmodulin as cofactors (Sessa, 1994). Three major isoforms of NOS have been described: neuronal NOS (NOS1 or nNOS), inducible NOS (NOS2 or iNOS), and endothelial NOS (NOS3 or eNOS).
