PHYSIOPATHOLOGICAL EFFECTS OF NITRIC-OXIDE AND ITS RELATIONSHIP WITH OXIDATIVE STRESS

Physiopathologic effects of nitric oxide and its relationship with oxi dative stress. Nitric oxide (NO .) is produced from L-arginine, as res ult of a reaction catalyzed by the enzyme nitric oxide synthase (NOS). The reaction is the sole source of NO . in animal tissues. NO . can c ontrol physiological processes (or systems) such as (a) blood pressure ; (b) relaxation of arterial smooth muscle; (c) platelet aggregation a nd adhesion; (d) neurotransmission; (e) neuroendocrine secretion. NO . contributes to the killing of patogenic microorganisms and tumoral ce lls by phagocytes. NO . reacts with superoxide anion thus producing pe roxynitrite, a cytotoxic ion capable of destroying many biological tar gets. The superoxide/peroxinitrite balance determines the ONOO- produc tion and, accordingly, is essential for the development of hypertensio n, atheroesclerosis, neurodegenerative diseases, viral infections, isc hemia-reperfusion injury, and cancer.