Nitric oxide, sepsis, and the kidney

Although excess nitric oxide (NO) production plays a major role in the hypotension characteristic of sepsis, concurrent constitutive NO generation in the kidney during sepsis is essential for preservation of renal perfusion and prevention of glomerular thrombosis. The authors have shown that although all nitric oxide synthase (NOS) inhibitors restore normal blood pressure in lipopolysaccharide (LPS) treated rats, only selective inducible NOS (iNOS) inhibition prevents the reductions in glomerular filtration rate (GFR), whereas nonselective inhibition of NOS further decreases GFR. Glomerular endothelial NOS (eNOS) activity was found to be inhibited by LPS. The decrease in eNOS activity was completely prevented by selective iNOS inhibition in vivo and in vitro. The adverse renal outcomes after LPS administration correlated with decreased glomerular eNOS activity rather than elevated NO production. These findings suggest that the decrease in GFR after LPS is caused by local inhibition of eNOS by iNOS possibly via NO autoinhibition. Selective inhibition of iNOS could represent a substantially superior approach for the treatment of the sepsis syndrome.