[The roles of alpha B-crystallin during early phase of myocardial ischemic preconditioning in rats].

This study designed to observe intracellular translocation of alpha B-crystallin, a small heat shock protein, and its possible implication during the early phase of myocardial ischemic preconditioning in isolated Langendorff rat hearts. Eighteen male Wistar rats(180-250 g) were randomly divided into three groups: 1. Control group(Ctrl) was perfused with K-H solution throughout the experiment; 2. ischemia-reperfusion group (I-R) experienced 30 min of global ischemia and 120 min of reperfusion and 3. preconditioning and ischemia-reperfusion group(PC + I-R) was preconditioned with three cycles of short myocardial ischemia(5 min each, separated by 5 min of reperfusion) prior to 30 min of ischemia and 120 min of reperfusion. It was showed that cytosolic soluble alpha B-crystallin rapidly translocated to insoluble intracellular structure after ischemic preconditioning, then gradually returned to soluble cytosol pool and almost completely recovered at about 60 min after preconditioning. In the meanwhile, ischemic preconditioning markedly alleviated subsequent myocardial ischemia-reperfusion injury, as indicated by the improvement of LVP, + dp/dt max, coronary flow, heart rate, CPK release and malondialdehyde(MDA) production. The results suggest that the intracellular translocation of alpha B-crystallin might be important for myocardial protection during the early phase of ischemic preconditioning.