The Study Of The Inducible HSP70 Gene Expression In The Ischemia-Reperfusion Rat Kidney

Objcctive: To inveStigate the expression of inducible HSP70 gene inischemia-reperfusion rat kidney. It includes: l. the iHSP70 gene expresses incourse of the comPlete ischemia; 2. the iHSP70 gene expression in course ofthe ischemia and reperfusion; 3. and comparison of the iHSP70 geneexpression in the different parts of rat kidney(the paPilla and the cortex)during this ischemia-reperfusion process.Methods: To evaluate the ischemia-reperfusion stimulus required to elicitiHSP70 gene expression, two animal models were perfOrmed of completeischemia and ischemia-reperfusion in situ in rat kidney: 1) variable ischemictime(10~60min) without reperfusion; 2) constant ischemic time with avariable period of reperfusion(2~72hours). Then homogenates of the kidneycortex and papilla were subjected to dot blot analysis. Semi-quantification ofthe dot blot bands density was carried out by laser densitometry comPuteranalyse.Results: In three variable ischemia grouPs(l0, 30, 60min) wtthoutreperfusion, the expression of iHSP70 gene as assessed by the dot blot greyvalue was not different between the ischemia grouPs and the contralateralnonischemic controls in kidney cortex and paPilla. In the constan period ofischemia(10min) and variable period of reflow(2hours--72hours), also notdifference were found between the processing groups and the controls inkidney cortex and paPilla. But in the constant period of ischemia(30min) andvariable period of refiow(2hours--48hours)we could find markedly greater inthe ischemia-reperfusion grouPs than in the controls. At the same time, byanalysis the expression level between the cortex and the paPilla in the sameischemia-reperf,sion condition, the paPilla was greater than the cortex(>3fold). There was no significan change in all the grouPs reflow(72hours).Similar reperfus io n -time - depend ent change s al s o be fO und in the grouP s o fischemia(60min) with a vedable reflow period(2--72hours).Conclusion: This study demonstrates that the gene expression of rat iHSP70occurs rapidly and time-dependent during renal ischemia-reperfusion processin sitU. Both a certain extellt ischemia and the subsequent period ofreperfusionare sufficient and necessary conditions to stimulate the gene expression of theiHSP70 in kidney. But the degree of kidney ischemic isn't parallel to theexpression strength of iHSP70. Take papilla and cortex for example, thedifferent magr itUdes of iHSP70 expression responsed to ischemia-reperfusionstimulus could be noticed within the different part of the kidney, higher inpapiIla.