Effects of ischemic preconditioning combined with postconditioning on renal ischemla-reperfusion injury in rats

Objective To evaluate the effects of ischemic preconditioning combined with postconditioning on the renal ischemia-reperfusion (I/R) injury in rats.Methods Thirty healthy male SD rats weighing 250-280 g were randomly assigned into 5 groups ( n = 6 each) : group Ⅰ sham operation (group S) ;group Ⅱ I/R;group Ⅲ ischemic preconditioning (group IP);group Ⅳ ischemic postconditioning (group IPo);group Ⅴ IP + IPo.The rats were anesthetized with intraperitoneal 10% choral hydrate.Bilateral kidneys were exposed through a midline incision and bilateral renal pedicels were occluded for 45 min followed by 6 h reperfnsion.In group S,the kidneys were exposed,hut their pedicles were not clamped.In group IP,bilateral renal pedicels were occluded for 5 min followed by 5 min reperfusion,repeating 3 times,and the other procedures were performed using the same method as that of group I/R.In group IPo,45 min ischemia was followed by three 10 s episodes of ischemia at 10 s intervals for reperfusion.Blood samples were taken from the hearts to determine serum creatinine (Cr) and urea nitrogen (BUN) concentrations.After the animals were killed at 6 h of reperfnsion,kidneys were immediately removed for determination of MAD content,SOD activity,and apoptosis in the renal tubular epithelial cells (using TUNEL assay),and observation of histopathology with light microscope.Apoptotic index (AI) was calculated.Results Compared with group S,serum Cr and BUN concentrations,MDA content and AI were significantly increased,whereas SOD activity decreased in the other 4 groups.Serum Cr and BUN concentrations,MDA content and AI were significantly decreased,SOD activity increased,and injury to kidney was attenuated in group IP,IPo and IP + IPo as compared with group I/R.SOD activity was significantly increased,AI decreased,and injury to kidney was attenuated in group IP + IPo as compared with group IP and IPo.Conclusion Ischemia preconditioning and postconditioning can ameliorate the renal I/R injury in rats by improving the antioxidation of the kidney and inhibiting the apoptesis in the renal tubular epithelial cells,and the efficacy is better than that of either IP or IPo alone. Key words: Ischemic preconditioning; Reperfusion injury; Kidney; Ischemic postconditioning