Effect Of Combination Of Ulinastatin, Ischemic Preconditioning And Ischemic Postconditiong On The Renal Ischemi-referfusion Injury In Rats

Objective To investigate the effect of combination of ulinastatin pretreatment, ischemic preconditioning and ischemic postconditioning on the renal ischemia-reperfusion (I/R) injury and its mechanism.Methods Thirty-six male SD rats weighing 250~280g were randomly allocated into 6 groups (n=6): groupⅠsham operation (S); groupⅡI/R; groupⅢischemic preconditioning + I/R + ischemic postconditioning (IP+IPo); groupⅣulinastatin + ischemic preconditioning + I/R (U+IP); groupⅤulinastatin + I/R + ischemic postconditioning (U+IPo); groupⅥulinastatin + ischemic preconditioning + I/R + ischemic postconditioning (U+IP+IPo). Bilateral kidneys were exposed through midline incision and bilateral renal pedicels were occluded 45 min with atraumatic mini-clamp then unclamped for 6 h. The kidneys turned kermesinus. In S group the kidneys were exposed but their pedicles were not clamped. In IP+IPo group, the kidneys were induced by 3 circles of ischemia (5 min) separated by reperfusion (5 min) before ischemia, and 45 min ischemia was followed by three 10 s episodes of ischemia at 10 s intervals for reperfusion. In U+IP group, ulinastatin 2×104 U/kg was given i.v. 30 min, then 3 circles of ischemia (5 min) separated by reperfusion (5 min) before ischemia-reperfusion injury. In U+IPogroup, ulinastatin 2×104 U/kg was given i.v. 30 min before ischemia and then 45 min ischemia was followed by three 10 s episodes of ischemia at 10 s intervals for reperfusion. In U+IP+IPo group, ulinastatin 2×104 U/kg was given i.v. 30 min before ischemia and the other operation same as IP+IPo group.The animals were killed at 6 h of reperfusion. Blood samples were collected from heart for determination of urea nitrogen(BUN) and serum creatinine(Cr) concentrations. Urine samples were collected from urinary bladder for determination ofα1-MG content. Kidney specimens were collected immediately for determination of MDA level and SOD activity, the expression of Bcl-2, Bax and Caspase-3 protein by immuno- histochemistry assay . The apoptosis in the nephridial tissue was assessed using TUNEL and apoptotic index(AI) was calculated.Results After I/R, the serum Cr and BUN concentrations, theα1-MG and MDA contents, the PI of Bax, Caspase-3 and the AI were all significantly increased while the SOD activity, the PI of Bcl-2 were significantly decreased as compared to the S group(P < 0.05).The Cr and BUN concentrations, theα1-MG and MDA contents, the PI of Bax, Caspase-3 and the AI were all significantly lower while the SOD activity, the PI of Bcl-2 were significantly higher in IP+IPo, U+IP, U+IPo and U+IP+IPo groups as compared with I/R group (P<0.05). The histologic damage induced by I/R were significantly ameliorated.Theα1-MG contents, the SOD activity and the AI were significantly lower in U+IP+IPo group than in U+IP group(P<0.05). The AI were significantly lower in U+IPo group than in U+IP group(P<0.05). The PI of Bcl-2 were significantly higher in U+IP+IPo group than in IP+IPo and U+IPo group(P<0.05). There were no significant difference in the rest indexes among the IP+IPo, U+IP, U+IPo and U+IP+IPo group.ConclusionIP+IPo, U+IP, U+IPo and U+IP+IPo can reduce the risk of renal dysfunction and injury associated with renal I/R injury by reducing apoptosis through enhancement SOD activity, increasing the expression of Bcl-2 protein, decreasing the Bax and Caspase-3 protein and regulating the Bcl-2 /Bax ratio accordingly. IP+IPo, U+IP, U+IPo and U+IP+IPo can protect the kidney against ischemia-referfusion injury in rats and U+IP+IPo is more effective.