Inhibition of nitric oxide synthase reduces renal ischemia/reperfusion injury.
BACKGROUND
The role of nitric oxide (NO) production because of inducible nitric oxide synthase (iNOS) in the pathogenesis of renal ischemia/reperfusion (I/R) injury is unclear. In this study the roles of both iNOS and NO were characterized in a rat model of renal I/R injury. In addition, the effect of iNOS inhibition on renal function was evaluated.


METHODS
Sprague-Dawley rats underwent 45 min of left renal ischemia and contralateral nephrectomy followed by various periods of reperfusion and renal function analysis [plasma creatinine, fractional excretion of sodium (FENa), creatinine clearance (CrCl), and measurement of plasma and urine NO levels]. In addition, the effect of treatment with 1400W, a highly selective iNOS inhibitor, was evaluated.


RESULTS
Renal dysfunction peaked at 48 h after reperfusion and immunohistochemistry studies revealed iNOS expression in the vasculature (3 h) and renal tubules (48 h) after reperfusion. Renal function improved significantly in treated animals compared to controls [creatinine of 1.1 v. 1.9 mg/dl (P < 0.05) and CrCl of 0.54 v. 0.31 ml/min (P < 0.05), respectively]. In addition, FENa was decreased by 50%, plasma NO levels were significantly lower (32.7 v. 45.7 micromol/L, P < 0.01), and deposition of nitrotyosine in the tubules of treated rats was less than in control animals.


CONCLUSIONS
These data support the hypothesis that iNOS and NO are involved in the pathogenesis of renal I/R injury and suggests that use of iNOS inhibitors may be a valuable therapeutic strategy clinical situations where renal I/R may be prevalent.
Mark
Lisa A
LA
Department of Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
Robinson
Ann V
AV
Schulak
James A
JA
D000578:Amidines / Q000494:pharmacology*; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology*; D003404:Creatinine / Q000097:blood; D004195:Disease Models, Animal; D016232:Endothelins / Q000097:blood; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007684:Kidney Tubules / Q000098:blood supply / Q000201:enzymology*; D008297:Male; D009569:Nitric Oxide / Q000097:blood; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D000578:Amidines; D001596:Benzylamines; D016232:Endothelins; D004791:Enzyme Inhibitors; C104820:N-(3-(aminomethyl)benzyl)acetamidine; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D003404:Creatinine; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat