However, eNOS-stimulated responses have been shown to be relatively preserved in patients with essential hypertension when compared with patients with other risk factors for cardiovascular disease, such as diabetes mellitus and hypercholesterolemia.25,26 Our findings provide a potential explanation for this discrepancy and raise the important question of whether nNOS dysfunction is an important contributor to hypertension. This evidence concerns the gene NOS1 and essential hypertension.