Exercise Training Protects Against Acute Myocardial Infarction via Improving Myocardial Energy Metabolism and Mitochondrial Biogenesis

Background/Aims: Acute myocardial infarction (AMI) represents a major cause of morbidity and mortality worldwide. Exercise has been proved to reduce myocardial ischemia-reperfusion (I/R) injury However it remains unclear whether, and (if so) how, exercise could protect against AMI. Methods: Mice were trained using a 3-week swimming protocol, and then subjected to left coronary artery (LCA) ligation, and finally sacrificed 24 h after AMI. Myocardial infarct size was examined with triphenyltetrazolium chloride staining. Cardiac apoptosis was determined by TUNEL staining. Mitochondria density was checked by Mito-Tracker immunofluorescent staining. Quantitative reverse transcription polymerase chain reactions and Western blotting were used to determine genes related to apoptosis, autophagy and myocardial energy metabolism. Results: Exercise training reduces myocardial infarct size and abolishes AMI-induced autophagy and apoptosis. AMI leads to a shift from fatty acid to glucose metabolism in the myocardium with a downregulation of PPAR-α and PPAR-γ. Also, AMI induces an adaptive increase of mitochondrial DNA replication and transcription in the acute phase of MI, accompanied by an activation of PGC-1α signaling. Exercise abolishes the derangement of myocardial glucose and lipid metabolism and further enhances the adaptive increase of mitochondrial biogenesis. Conclusion: Exercise training protects against AMI-induced acute cardiac injury through improving myocardial energy metabolism and enhancing the early adaptive change of mitochondrial biogenesis.