PROTECTION OF ISCHEMIC RENAL INJURY BY RENAL ISCHEMIC PRECONDITIONING: POSSIBLE ROLE OF NITRIC OXIDE

P52 Aims: Ischemic preconditioning, a phenomenon induced by brief ischemia and reperfusion periods, renders an organ tolerant to subsequent prolonged ischemia. This study evaluated different schedules of preconditioning the kidney to assess the role of nitric oxide (NO) and determine the effects of preconditioning on kidney transplantation. Methods: Ischemic preconditioning, which consists of three cycles of 2-minute ischemia followed by 5-minute reperfusion, was performed prior to 45-minute ischemia.. Results: Ischemic preconditioning significantly improved the renal dysfunction induced by 45-minute ischemia followed by 24-hour reperfusion. Histopathological examination of the kidney of ischemia/reperfusion rats revealed severe renal damage, and suppression of the damage was seen with the ischemic preconditioning treatment. NO metabolites (NOx) production in the kidney after 45-minute ischemia and reperfusion was markedly increased in ischemia/reperfusion rats with ischemic preconditioning, compared with animals not subjected to ischemic preconditioning. The levels of renal antioxidant enzymes were significantly improved by ischemic preconditioning as compared to ischemia/reperfusion rats. The improvement of renal dysfunction in ischemic preconditioning rats was abolished by the pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), a nonselective NOS inhibitor. Conclusions: Ischemic preconditioning has a protective effect on renal structure and function and these findings suggest that the protective effect of ischemic preconditioning on ischemia/reperfusion -induced acute renal failure is closely related to the renal nitric oxide production.