Remote ischemic preconditioning enhances the effect of aerobic exercise on cardiac endoplasmic reticulum stress in rats with myocardial infarction model

Objectives: Cardiac endoplasmic reticulum (ER) stress through accumulation of misfolded proteins plays a pivotal role in cardiovascular diseases. Exercise training may be a potential strategy to reestablish cardiac ER homoeostasis. Ischemic preconditioning (IPC) has a protective effect against myocardial injury, however, its effects with exercise training remain unclear. The present study aimed to investigate the effect of aerobic training and IPC on myocardial PERK and ATF6 gene expression in rats with myocardial infarction (MI).
Materials and Methods: In this experimental research, 35 wistar rats were randomly divided into seven groups: control (C), MI, MI one-leg ischemia (1IP), MI two-leg ischemia (2IP), MI aerobic training (T), MI one-leg ischemia+ training (1IPT), MI two-leg ischemia+ training (2IPT). MI was induced by injections of Isoproterenol (100 mg/kg.day) on two doses. IPC included three 5-minute cycles of ischemia, followed by five minutes of reperfusion. The aerobic training was performed for six weeks and 5 sessions/week. PERK and ATF6 gene expression was measured by RT-PCR method. Data were analyzed by one-way ANOVA test.
Results: PERK and ATF6 gene expression significantly increased in MI compared to C. PERK and ATF6 decreased significantly in 1IP (P=0/032, P=0/001), 2IP (P=0/004, P=0/003), T (P=0/001, P=0/001), 1IPT (P=0/0001, P=0/001) and 2IPT (P=0/0001, P=0/0001) compared to the C.
Conclusion: Aerobic training, and ischemic preconditioning, both unilateral and bilateral, improved cardiac endoplasmic reticulum stress in rat models of myocardial infarction. However, aerobic exercise combined with ischemic preconditioning demonstrated a more pronounced effect.