Association Between Nadph Oxidase Activity And No Bioavailability In Human Blood Arteries Of Hyperhomocysteinemic Patients

Nitric oxide (NO) deficiency is a hallmark of the vascular disorders induced by risk factors, including hyperhomocysteinemia (Hhcy). NADPH oxidase and eNOS are sources of reactive oxygen and nitrogen species (NROS). Hhcy can promote NROS stress leading to the endothelial dysfunction. Here we investigated the mechanism of NROS stress in the endothelium of patients with induced Hhcy. Patients qualified for the carotid endarterectomy received 100 mg/kg p.o. methionine or placebo 6 h before surgery. Fragments of isolated carotid arteries were used in the study. NADPH oxidase activity was measured with lucigenin‐based assay. NO, O 2 ‐ and peroxynitrite (ONOO ‐ ) release from endothelial cells (ECs) were measured using electrochemical nanosensors. The expressions of eNOS and NADPH oxidase subunits were analyzed by Western blotting. Hhcy group revealed significant increase of NADPH oxidase activity and the expression of total and membrane fractions of p47phox subunit. eNOS stimulation resulted in lower NO levels and increased production of both O 2 ‐ and ONOO ‐ in group with Hhcy. The presence of apocynin improved NO release in ECs with Hhcy. eNOS expression was significantly higher in the Hhcy ECs. The ratio of eNOS dimers to the total eNOS was significantly decreased in patients with Hhcy. In conclusion, the disruption of dimeric structure of overexpressed eNOS contributes to overproduction of O 2 ‐ and induction of eNOS‐dependent NROS stress in patients with Hhcy.