Lack of evidence for contribution of intron4a/b polymorphism of endothelial nitric oxide synthase (NOS3) gene to plasma nitric oxide levels.

Abstract

Nitric oxide (NO) is synthesized from L-arginine by endothelium nitric oxide synthase (NOS3). It has been shown that reduced NO synthesis in endothelial cells has been implicated in the development of coronary atherosclerosis. We hypothesized that polymorphisms of NOS3 gene might be associated with increased susceptibility of coronary artery disease (CAD) and plasma NO concentrations.
We studied the NOS3 intron4 gene polymorphism in 141 unrelated CAD patients with positive coronary angiograms in the Shahid Rajaee Heart Hospital and 159 age-matched control subjects without a history of symptomatic CAD. The NOS3 gene polymorphism was analysed by polymerase chain reaction. Plasma NO was also determined. The genotype frequencies for NOS34a/b polymorphism differed significantly between CAD patients and controls (P = 0.041). Mean plasma NOx concentration was significantly higher (P = 0.0009) in CAD patients (87.5 microM) than in controls (62.7 microM). Mean plasma NOx concentrations in the subjects with 4a allele and in the subjects without 4a allele were not significantly different. Plasma lipids, except HDL-C were also remarkably increased in the CAD group.
The present study provides evidence that the intron4a/b polymorphism of the NOS3 gene is associated with CAD. Mean plasma NO was higher in CAD patients than in control subjects. The NOS34a/b polymorphism was not associated with increased plasma NO.