The augmentative effect of repeated heat shock preconditioning on the production of heat shock protein 72 and on ischemic tolerance in rat liver tissue

Objective: Heat shock pretreatment induces heat shock protein (HSP) 72 stro ngly in rat livers and provides the tolerance against subsequent ischemia-r eperfusion injury. In this study, the effects of repeated heat shock pretre atment on the production of HSP72 in rat livers and on subsequent ischemic tolerance were investigated. Methods: Rats pretreated with repeated heat shock were compared with those that received a single heat shock pretreatment. The production of HSP72 was analysed using Western-blotting and densitometer. At 48 h after heat shock pretreatment, all rats were subjected to warm liver ischemia for 30 or 45 min and then reperfused. Survival rate of the animals and liver functions d uring reperfusion were analysed. Results: The production of HSP72 increased in the repeated heat shock group more than in the single heat shock group. Although there were no significa nt differences in animal survival or in liver functions after a 30-min isch emia between the single heat shock group and the repeated heat shock group, animal survival and liver functions after a 45-min ischemia were significa ntly better in the repeated heat shock group. Conclusion: In rats, repetition of heat shock pretreatment augmented the pr oduction of HSP72 in liver tissue and protected the liver from ischemia-rep erfusion injury.