Serum nitric oxide metabolite (NO(x)) levels in hypertensive patients at rest: a comparison of age, gender, blood pressure and complications using normotensive controls.

1. Hypertensive patients have pathophysiological changes such as atherosclerosis, endothelial dysfunction and inflammations. The patients' serum nitric oxide metabolite (nitrate/nitrite; NO(x)) levels were measured in peripheral blood using normotensive controls for comparison. 2. The NO(x) levels in 175 hypertensive patients with or without comorbid diseases (aged 37-95 years; average 50.6 +/- 0.8 years) were compared with those in 80 normotensive controls (aged 25-73 years; average 37.1 +/- 1.8 years). 3. The NO(x) levels increased with age in both the normotensive and hypertensive women, but not in men. No difference was noted in the NO(x) levels between the normotensive and hypertensive patients without comorbid diseases. The mean value of NO(x) in male hypertensive patients aged under 50 years was close to that of female patients aged 51-60 years. Hypertensive males aged 61-70 years showed almost the same NO(x) levels as those of female patients aged over 81 years. A male group of hypertensive patients with diabetes, hyperlipaemia and renal disorder had a significantly higher NO(x) level compared with a normotensive control group. However, in female groups, only hypertensive patients with hyperlipaemia showed higher serum NO(x) values compared with the normotensive group. 4. These findings suggest that: (i) the occurrence of NO(x) in the serum is not solely the outcome of high blood pressure; (ii) higher serum NO(x) levels in older women are because of an oestrogen deficiency-induced cardiovascular disease; (iii) ageing effects on the circulation system are more apparent in men than in women; and (iv) measurement of NO(x) levels in the serum is helpful for understanding the pathological progress in male hypertensive patients with diseases such as diabetes mellitus, hyperlipaemia and renal disorder.