Introduction: Exercise Training (ET) has a cardioprotective effects and can induce new cardiomyocyte formation in physiological cardiac remodeling. However, following a large Myocardial Infarction (MI), the alterations of cardiac regeneration subsequent with different intensities of ET remains unexplored. The purpose of this study was to investigate the effect of exercise training intensity on cardiac regeneration capacity in rats with Myocardial Infarction (MI).
Methodology: Male Wistar rats were exposed to LAD coronary artery ligation surgery and then confirmed by echocardiography creation of MI. Four weeks after surgery, the rats with MI were divided randomly in four groups including Low Intensity Training (LIT), Moderate Intensity Training (MIT), High Intensity Training (HIT), and Sham. Training groups performed exercise training protocols for 6 weeks, five sessions in a week. The rats were sacrificed after the exercise training interventions, and the data obtained from their cardiac tissues by RT-PCR technique, via one-way ANOVA and LSD tests, were analyzed.
Results: ANOVA test results showed that values of ejection fraction, fractional shortening, mRNA Gata4, and mRNA Tbx5 had a significant difference among all groups (P=0.000). LSD test results demonstrated that ejection fraction and fractional shortening values (except for group LIT) in the exercise training groups increased significantly compared to Sham group. However considering increase, values in the Con group is significantly higher than the groups with MI. Results also showed that mRNA Gata4 value in the LIT group significantly increased compared to the MIT, HIT, Sham, and Con groups. Nevertheless, mRNA Tbx5 value in the LIT group insignificantly increased compared to MIT, HIT and Sham groups. mRNA Tbx5 value in the Con group is significantly higher than the groups with MI.
Discussion: In conclusion, it seems that exercise training, regardless the intensity, increases cardiovascular function in rats with MI. However, Low Intensity Exercise is probably a more effective agent in increasing cardiac regeneration capacity rats with MI.