Heat shock pretreatment in inhibiting myocardical apoptosis induced by ischemia-reperfusion and its mechanism

Objective: To explore the mechanisms of myocardial apoptosis during myocardial ischemia-reperfusion injury and to further clarify the molecular mechanisms by which heat shock pretreatment in inhibiting myocardial apoptosis induced by ischemia-reperfusion injury. Methods: Myocardial ischemia-reperfusion injury was induced by the occlusion of left anterior descending branch of the coronary artery. Apoptosis was evaluated by DNA laddering assay and the activities of caspase 3, 8, or 9 was measured with Caspase Colorimetric Assay Kit. Expression of heat shock proteins was detected by Western blottting analysis. To explore the effect of heat shock pretreatment on myocardium against apoptosis, mice were pretreated with whole body hyperthermia before the myocardial ischemia-reperfusion injury. Results: Ischemia-reperfusion injury induced myocardial apoptosis and activation of caspase-3, 8, 9. Heat shock pretreatment induced the expression of several family members of heat shock proteins and inhibited myocardial apoptosis and activation of the above caspases. Conclusion: Mitochondria and death receptor signaling pathways play important roles in myocardial apoptosis induced by ischemiareperfusion injury. Heat shock pretreatment may increase the expression of several HSP, and inhibit the activation of both mitochondria and death receptor signaling pathways and apoptosis in cardiomyocytes induced by myocardial ischemia-reperfusion injury.