Preconditioning Effect of High-Intensity Aerobic Training on Myocardial Ischemia-Reperfusion Injury and Beclin-1 Gene Expression in Rats

Purpose: Ischemia-Reperfusion (IR) injury is one of the most common cardiac disorders leading to irreversible heart damage. Many underlying mechanisms seem to be involved, among which disruption of cellular autophagy balance. Since physical training has a beneficial effect on the improvement of autophagy balance, it may have a cardioprotective effect against IR injury. This study investigates the protective role of aerobic training from cardiac IR injury and the autophagy process as a possible mechanism. Methods: Thirty-two male Wistar rats (8 weeks old) were divided into control, sham, control plus IR, and training plus IR groups (8 rats each). The training group was exercised aerobically on a treadmill for 8 weeks (5 d/wk). After 8 weeks, the anesthetized rats underwent left thoracotomy (sham, control plus IR, and training plus IR groups) to access the left anterior descending coronary artery, which was occluded by a silk suture for 30 min and then released for 90 min of reperfusion (IR groups). Triphenyltetrazolium chloride staining was used to determine the infarct size. The gene expression of Beclin-1 was evaluated by real-time polymerase chain reaction. One-way ANOVA was used for statistical analysis with the significance level set at P≤0.05. Results: The cardiac infarct size was smaller in training plus IR (20.24±5.7%) group compared to that in the control plus IR (35.9±2.3%) group (P≤0.05). On the other hand, IR operation significantly increased the gene expression of Beclin-1, while exercise training prevented expression of the mentioned gene in training plus IR group (P≤0.05). Conclusion: Aerobic training can protect the heart against Ischemia-Reperfusion injury. It seems that improvement of autophagy balance during IR injury may be involved in exercise-induced cardioprotection against Ischemia-Reperfusion.