Atheroprotective NO is mainly produced by enzyme endothelial nitric oxide synthase (eNOS), which is a dimeric NOS isoform specifically expressed in endothelial cells and known as an endothelial protective factor in atherosclerosis while the inducible nitric oxide synthase (iNOS), another NOS isoform induced by cytokines and other agents expressed in almost any cell type, shown to be proatherogenic (13). This evidence concerns the gene NOS3 and atherosclerosis.