Resistance exercise mediates remote ischemic preconditioning by limiting cardiac eNOS uncoupling

BACKGROUND

Currently viewed as a complementary non-pharmacological intervention for preventing cardiac disorders, long-term aerobic training produces cardioprotection through remote ischemic preconditioning (RIPC) mechanisms. However, RIPC triggered by acute exercise remains poorly understood. Although resistance exercise (RE) has been highly recommended by several public health guidelines, there is no evidence showing that RE mediates RIPC. Hence, we investigated whether RE induces cardiac RIPC through nitric oxide synthase (NOS)-dependent mechanism.

METHODS AND RESULTS

Acute RE at 40% of the maximal load augmented systemic nitrite levels, associated with increased cardiac eNOS phosphorylation, without affecting nNOS activity. Using an experimental model of myocardial infarction (MI) through ischemia-reperfusion (IR), RE fully prevented the loss of cardiac contractility and the extent of MI size compared to non-exercised (NE) rats. Moreover, RE mitigated aberrant ST-segment and reduced life-threatening arrhythmias induced by IR. Importantly, inhibition of NOS abolished the RE-mediated cardioprotection. After IR, NE rats showed increased cardiac eNOS activity, associated with reduced dimer/monomer ratio. Supporting the pivotal role of eNOS coupling during MI, non-exercised rats displayed a marked generation of reactive oxygen species (ROS) and oxidative-induced carbonylation of proteins, whereas RE prevented these responses. We validated our data demonstrating a restoration of physiological ROS levels in NE + IR cardiac sections treated with BH₄, a cofactor oxidatively depleted during eNOS uncoupling, while cardiac ROS generation from exercised rats remained unchanged, suggesting no physiological needs of supplemental eNOS cofactors.

CONCLUSION

Together, our findings strongly indicate that RE mediates RIPC by limiting eNOS uncoupling and mitigates myocardial IR injury.