Heat shock preconditioning on mitochondria during warm ischemia in rat livers

Background. The aim of this study was to investigate the effects of stress tolerance from heat shock preconditioning on changes in mitochondrial funct ions during ischemia-repel fusion injury of the liver. Materials and methods. Rats were divided into a heat shock group (group HS) and a control group (group C), In group HS, rats received heat shock pretr eatment 48 h prior to ischemia-reperfusion. Heat shock pretreatment was per formed in a water bath at 42 degrees C for 15 min under general anesthesia. In group C, the same treatment was done with the water bath at 37 degrees C instead of at 42 degrees C, A 30-min warm ischemia by cramping the hepato duodinal ligament (Pringle's maneuver) followed by a 60-min reperfusion was administered to all rats. Changes in membrane potential of hepatic mitocho ndria (MPM); mitochondrial respiratory function before ischemia (n = 5), af ter ischemia (n = 10), and after reperfusion (n = 10); and ATP recovery aft er reperfusion were compared between the groups. Results. After a 30-min ischemia, MPM in group C decreased significantly an d did not recover even after reperfusion, On the other hand, MPM in group H S was maintained even after a 30-min ischemia and 60 min into reperfusion a s well, The respiratory control ratio (RCR) of the mitochondria in group C decreased to as low as 5.06 +/- 0.72 after a 30-min ischemia, but in group HS, RCR was maintained near a normal level. The ATP level recovered signifi cantly earlier in group HS than in group C after reperfusion, Conclusions. Heat shock preconditioning of the liver protected mitochondria from loss of membrane integrity during ischemia and contributed to their a bility to produce energy-rich phosphates during reperfusion, a 1999 Academi c press.