Analysis of nitric oxide in the exhaled air of patients with chronic glomerulonephritis

Nitric oxide (NO) plays an important role in renal hemodynamics and function. Although production of NO in the glomeruli has been found to be increased in animal models of glomerulonephritis, it remains unclear whether its endogenous production is enhanced in patients with chronic glomerulonephritis (CGN).

We measured NO output in exhaled air as an indicator of its local production in the lungs and plasma and urinary nitrite plus nitrate (NO2-/NO3-) levels as indicators of its production in the whole body in 21 patients with CGN in 31 healthy controls.

The patients exhaled higher concentrations of NO (29.5 +/- 1.4 vs. 18.7 +/- 1.0 parts per billion (ppb), mean +/- SEM, p < 0.0001) and exhaled NO output was also higher than in controls (166.6 +/- 6.8 vs. 95.5 +/- 5.6 nl/min/m2, p < 0.0001). Plasma NO2-/NO3- concentrations were also significantly greater in the patients than in the controls (81.6 +/- 7.2 vs. 41.1 +/- 4.3 micromol/l, p < 0.001). In patients with CGN, exhaled NO output correlated negatively with creatinine clearance (r = -0.62, p < 0.05). Oral administration of prednisolone (60 mg/day) for two weeks did not significantly affect the exhaled NO output in the patients (160 +/- 7 vs. 200 +/- 30 nl/min/m2, p = NS) despite a decrease in urinary protein excretion (12.0 +/- 2.9 vs. 1.4 +/- 0.6 g/day, p < 0.01).

These findings suggested that endogenous NO production is increased in patients with CGN. Increased endogenous NO production may play some pathophysiological role in these patients.