Age-associated changes in nitric oxide metabolites nitrite and nitrate

Aging is an important determinant of vascular disease. Endothelial dysfunct ion accompanying vascular disease may be related to cardiovascular risk fac tors such as aging, hypertension, and atherosclerosis. Experimental models suggest that endothelium-derived nitric oxide is reduced with aging, and th is reduction is implicated in atherogenesis. The aim of this study was to d etermine whether increased age resulted in altered serum nitrite and nitrat e levels, end-products of nitric oxide, in healthy subjects. Sixty-nine hea lthy individuals were divided into five different age groups: group I (6-15 years), group II (16-30 years), group III (31-45 years), group IV (46-60 y ears), and group V (>61 years). In these subjects, serum nitrite was measur ed by the Griess reaction and nitrate by the nitrate reductase method. Stat istical analysis showed that serum nitrite levels were not significantly di fferent in any of the groups, while serum nitrate concentrations exhibited significant differences (P<0.001). These findings suggest that nitric oxide synthesis and/or secretion is reduced with age and consequently endotheliu m-dependent vasodilation is impaired.