Expression and Activity of Platelet Endothelial Nitric Oxide Synthase Are Decreased in Patients with Coronary Thrombosis and Stenosis

BACKGROUND: Nitric Oxide (NO) which is synthesized by endothelial Nitric Oxide Synthase (eNOS) in both vascular tissues and platelets plays an important role as a protective mediator in the cardiovascular system. It modulates blood pressure, vasodilation and thrombosis. In this regard, eNOS activity and gene expression in platelets and NO levels in patients’ plasmas with Coronary Thrombosis (CT) and stenosis diseases were determined. METHODS: Blood samples were collected from 60 subjects that where divided into three equal groups [without coronary artery disease, with CT and less than 70% Coronary Stenosis (CS)]. NO concentration in plasma was measured by the Griess reagent system. The eNOS activity was assessed based on a fluorimetric detection system in platelets and the gene expression was quantified by the real time-reverse transcription-polymerase chain reaction. RESULTS: There was a significant decrease in the amount of NO concentration in the plasma of subjects with CT (0.53±0.09 μM, p<0.01) and CS (1.31±0.11 μM, p<0.01) compared to the control group (2.6±0.10 μM). The activity levels of eNOS enzyme were significantly lower in patients’ platelets with CT (0.68±0.013 UF/mn, p<0.01) and CS (0.85±0.017 UF/mn, p<0.01) than the control cases (1.29±0.019 UF/mn). These data were consistent with the reduction of the expression levels of eNOS in patients with CT (75 folds) and CS (4 folds) lower than the control cases. CONCLUSION: Patients with CT and CS possessed reduced eNOS activity and gene expression in their platelets. Decreased plasma concentration of NO in these patients confirmed the potential significance of the diagnostic and prognostic value of NO in the subjects’ plasma with vascular disease risk.