Nitric oxide synthase 1 (NOS1) (nNOS)

Neuronal nitric oxide synthase (nNOS), specifically the nNOSμ splice variant, is a key enzyme in skeletal muscle responsible for producing nitric oxide (NO) from L-arginine (UniProt P29475). In healthy muscle fibers, nNOS is localized to the sarcolemma through its interaction with the dystrophin-glycoprotein complex (DGC), specifically binding to alpha-syntrophin (PubMed: 10617630). This localization is crucial for "functional sympatholysis," a process where NO attenuates alpha-adrenergic vasoconstriction to ensure adequate blood flow to contracting muscles (PubMed: 22431541). In pathologies such as Duchenne muscular dystrophy (DMD), the loss of the DGC leads to the displacement of nNOS into the cytosol, where it is often degraded, resulting in reduced NO bioavailability and subsequent muscle ischemia and fatigue (PubMed: 18463627). Pharmacological targeting of the nNOS pathway includes the use of selective inhibitors for neurological conditions or the use of downstream modulators like PDE5 inhibitors to compensate for reduced NO signaling in muscular dystrophies (PubMed: 24503015).

Other names

Neuronal nitric oxide synthasenNOSmunNOS-muNOS-IbNOSNitric oxide synthase, brainNOS1

Direct inhibition of the enzyme's catalytic activity by competing with the substrate L-arginine or interfering with cofactor binding, thereby reducing the production of nitric oxide (PubMed: 10617630).