Nitric oxide synthase 3 (Endothelial nitric oxide synthase) (eNOS)

Endothelial nitric oxide synthase (eNOS), also known as Nitric oxide synthase 3 (NOS3), is a constitutive enzyme primarily expressed in vascular endothelial cells (UniProt: P29474) [1]. It plays a fundamental role in cardiovascular homeostasis by catalyzing the production of nitric oxide (NO) from L-arginine, which acts as a potent vasodilator and inhibitor of platelet aggregation and leukocyte adhesion (StatPearls: Physiology, Nitric Oxide) [2]. Dysregulation of the eNOS/NO pathway, often characterized by 'eNOS uncoupling' where the enzyme produces reactive oxygen species instead of NO, is a central feature of endothelial dysfunction in diseases such as atherosclerosis, hypertension, and diabetes (PubMed: PMC3430443) [3]. Pharmacological modulation of this pathway includes the use of NO donors like nitroglycerin, phosphodiesterase-5 (PDE5) inhibitors like sildenafil, and soluble guanylate cyclase (sGC) stimulators like riociguat to enhance NO signaling (DrugBank: DB00627) [4]. Additionally, certain drugs like nebivolol and statins have been shown to increase eNOS activity or expression, providing further therapeutic avenues for treating cardiovascular conditions [5].

Other names

NOS3Endothelial NOSConstitutive NOScNOSNitric oxide synthase, endothelial

The eNOS enzyme catalyzes the conversion of L-arginine and oxygen into L-citrulline and nitric oxide (NO) in the presence of cofactors like tetrahydrobiopterin (BH4). NO then diffuses into adjacent vascular smooth muscle cells where it binds to and activates soluble guanylate cyclase (sGC), leading to the production of cyclic guanosine monophosphate (cGMP), which triggers vasorelaxation and inhibits cellular proliferation (StatPearls: Physiology, Nitric Oxide) [2].