Effect of Ischemic Postconditioning on Renal Ischemia-Reperfusion Injury in Male Rats

Background: Several recent studies have shown that a brief ischemia applied during the onset of reperfusion (postconditioning) is cardioprotective in different animal models. The potential trial of postconditioning in kidney is few. The present study investigated the hypothesis that postconditioning can improve I/R associated oxidative-stress and subsequently improve renal function. Method: Three groups (n=24/group) were included in this study: sham operated, I/R and I/R-postconditioned groups. Bilateral renal ischemia for 45 min was followed by complete blood flow restoration without intervention in the I/R group and in the postconditioned group, complete reperfusion was preceded by 3 min, 6 min and 12 min of reperfusion in a consecutive sequence, each separated by 5 min of reocclusion. Animals were studiedfor 48 h. Results: Blood urea nitrogen, serum creatinine, urine K^+ and fractional Na^+ excretion were significantly elevated 24 and 48 h following reperfusion in the I/R group compared to those of the sham group at similar time respectively. Postconditioning significantly decreased these parameters compared to I/R group at similar time of reperfusion. Postconditioning also significantly reduced I/R- induced increase in superoxide anion production at 36 min, 24 and 48 h of reperfusion as well as in the neutrophil/ monocytes myeloperoxidase activity at 36 min of reperfusion. Renal malondialdehyde and hemoxygenase-I (HO-I) expression were significantly increased and renal anti-oxidant enzymes glutathione reductase and superoxide dismutase were significantly decreased by I/R at 36 min, 24 and 48 h following reperfusion and they were significantly improved by postconditioning in the I/R-postconditioned group. Kidneys from the 1/R-postconditioned group showed a significantly lower necrosis score of I (patchy isolated damage) at 24 and 48 h compared to the I/R group necrotic score of 3 (up to 50% damage) at the same time. Conclusion: Postconditioning improved renal function, morphology and oxidant/antioxidant system and reversed I/Rinduced increase in HO-I expression in the kidney. Postconditioning can be considered as a potential promising strategy at the onset of reperfusion following renal ischemia.