Exercise Training Stabilizes RyR2-Dependent Ca²⁺ Release in Post-infarction Heart Failure

Area of Science:

• Cardiology
• Exercise Physiology
• Molecular Biology

Background:

• Cardiac ryanodine receptor 2 (RyR2) dysfunction is common in heart failure (HF), leading to abnormal calcium (Ca2+) release, contractile issues, and arrhythmias.
• Exercise training (ET) is a guideline-recommended therapy for HF, but its effects on RyR2 function require further investigation.

Purpose of the Study:

• To investigate the potential of high-intensity interval ET to stabilize RyR2-dependent Ca2+ release in rats with post-myocardial infarction HF.
• To assess the impact of ET on aerobic capacity, cardiac function, and Ca2+ handling in HF rats.

Main Methods:

• Male Wistar rats underwent myocardial infarction or sham surgery, followed by randomization to ET or sedentary behavior (SED) for 5 weeks.
• Echocardiography assessed cardiac function, while left ventricular cardiomyocytes were analyzed for Ca2+ release. Beta-adrenoceptor density was quantified.
• VO2max tests determined exercise intensity and aerobic capacity.

Main Results:

• ET significantly increased VO2max in HF rats compared to SED controls.
• ET attenuated spontaneous Ca2+ release from the sarcoplasmic reticulum (SR) in cardiomyocytes but also reduced Ca2+ transient amplitude and slowed reuptake during beta-adrenoceptor activation.
• Ventricular function remained unchanged, and SR Ca2+ regulatory proteins did not show significant alterations. Beta-adrenoceptor normalization was observed.

Conclusions:

• Exercise training enhances aerobic capacity and stabilizes RyR2-dependent Ca2+ release in post-infarction HF rats.
• These benefits of ET can be achieved without major changes in SR Ca2+ regulatory proteins.
• Future research should explore upstream components of the sympathetic signaling pathway involved in ET's effects on HF.