Glomerular nitrite synthesis in in situ immune complex glomerulonephritis in the rat

Nitrite (NO2-) is the major end product of nitric oxide (NO) production in cell culture. The authors have examined nitrite production by glomeruli in in situ immune complex glomerulonephritis in the rat. Glomerulonephritis was induced by unilateral renal perfusion of cationized human gamma G immunoglobulin (IgG) in preimmunized rats. NO2- was measured in culture supernatants of isolated glomeruli after 48 hours. NO2- was produced by nephritic glomeruli with a maximum 4 days after induction of glomerulonephritis (24.4 +/- 11.4 pmol/glomerulus/48 hours). Production was increased by lipopolysaccharide (LPS; 1 micrograms/ml) (54 +/- 4.9 pmol/glomerulus; P less than 0.001). NO2- production was inhibited by the nitric oxide synthase inhibitor NG-monomethyl-L-arginine demonstrating synthesis through NO. Dexamethasone (10(-7) mol/l [molar]) reduced LPS-stimulated production by peritoneal macrophages and nephritic glomeruli (P less than 0.01). Macrophages isolated from nephritic glomeruli produced NO2- (4.9 +/- 0.6 nmols/10(5) cells). The production of NO by nephritic glomeruli has implications for mechanisms of glomerular injury and glomerular hemodynamics. The effect of dexamethasone may explain in part the ameliorative effect of steroids in glomerulonephritis.