| Objectives To establish the rats' model of ischemia-reperfusion(IR), erythropoietin(EPO) post-conditioning and ischemia post-conditioning(IPO). To observe the protective effect of erythropoietin post-conditioning after rats' renal ischemia-reperfusion injury. To investigate the effect of erythropoietin postconditioning on expression of HIF-1? and HSP-70 in rats after renal ischemia reperfusion injury. To compare the different effects of erythropoietin postconditioning and ischemia postconditioning in rats' renal ischemiareperfusion injury.Methods Forty-eight healthy male Sprague-dawly rats were randomly divided into four groups, twelve rats each,(1) sham group(S group): the left renal pedicle was separated and the right one was ligatured after anesthesia, then they were exposed for 45 min.(2)ischemia-reperfusion group(IR group): the left renal pedicle was clamped for 45 min soon after reperfusion, which was based on method of S group.(3) postconditioning group(IPO group): sequential 10 sec reperfusion and another 10 sec ischemia for 6cycles 5 min before kidney reperfusion, which was based on method of IR group.(4)erythropoietin postconditioning group(EPO group): erythropoietin was intravenous injected at 3000u/kg 5min before reperfusion, which was based on method of IR group.Six rats were randomly selected from each group above and taken serum samples three hours after reperfusion. And they were killed six hours after reperfusion for the serum and kidney samples. Serum samples were taken twelve hours after reperfusion of the rest rats, serum and kidney samples were taken twenty-four hours after reperfusion. Serum urea nitrogen and creatinine were detected by chemical method; serum MDA was measured by thiobarbituric acid(TBA) and serum SOD was measured by xanthineoxidation(XOD). The pathological changes in kidneys were observed by HE staining.The expression of HIF-1? and HSP-70 were detected by immunohi-stochemistry staining technique and analysised by image analysis system.Results Compared with S group, BUN and SCr were increased significantly in experimented groups(P<0.05). Compared with IR group, the BUN and SCr levels of IPO group and EPO group were generally lower significantly(P<0.05). Compared with EPO group, the overall BUN and SCr levels of IPO group were not different significantly(P>0.05). 2. Compared with S group, the SOD activity was decreased significantly and the level of MDA was increased significantly in experimented groups(P<0.05).Compared with IR group, the overall SOD activity were increased significantly, while the overall MDA level were decreased significantly of IPO group and EPO group(P<0.05).Compared with the EPO group, the overall SOD activity and MDA level in IPO group were not different(P>0.05).3.Abnormalities was not seen in S group. Compared with S group, injuries were obviously severer in IR group that renal tubular epithelial cell became swelling and necrosis, cast formation obviously in renal tubular, many inflammatory cell infiltrated in IR group. While in EPO group, the swelling of tubular epithelial became lighter, the amount of cell necrosis decreased, inflammatory cells and casts were rare. Compared with the EPO group, injuries in IPO group were basically the same. The comparison in each group shows that the injuries of twenty-four hours after reperfusion is more severer than them in six hours'.4.The expression of HIF-1? was not showed in S group. Compared with S group, the expression of HIF-1? was significantly increased in renal tubular epithelial cells of opearation groups(P<0.05). The expression of HIF-1? in operation groups was significantly increased in six hours after reperfusion, but lower than it in twenty-four hours after reperfusion(P<0.05). Compared with IR group,the expression of HIF-1? was significantly increased in EPO group(P<0.05). The expression of HIF-1? between EPO group and IPO group had no significant differences(P<0.05).The expression of HSP-70 wasn't showed in S group. Compared with S group, the expression of HSP-70 was significantly showed in renal tubular epithelial cells of operation groups(P<0.05). The expression of HSP-70 in EPO group at six hours after reperfusion was strongly positive, and significantly decreased at twentyfour hours after reperfusion(P<0.05). Compared with EPO group, the expression of HSP-70 in IR group was significantly weaker both in six and twenty-four hours after reperfusion(P<0.05). Compared with the EPO group, the expression of HSP-70 in IPO group had no significant difference(P>0.05).Conclusions 1. Erythropoietin post-conditioning have protective effect on renal IRI in rats. 2. Erythropoietin post-conditioning may increase the expression of HIF-1? and HSP-70 to produce the protective effect on renal IRI in rats. 3. Erythropoietin postconditioning have the same protective effect with IPO on renal IRI of rats. |
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