Exercise training improves functional post-ischemic recovery in senescent heart

Abstract

The incidence of ischemic cardiac diseases increases with age and elderly subjects are more vulnerable to myocardial infarction. Endurance exercise (e.g. treadmill training) provides cardioprotection against an ischemia and reperfusion (IR) event in adult heart but such a potential beneficial effect of regular exercise has never been evaluated during aging. Therefore, this study investigated the effects of moderate running training on post-ischemic recovery of contractile function and coronary perfusion in senescent myocardium. Isolated hearts of sedentary (24 mo-sedentary; n = 10) and trained senescent (24 mo-trained; n = 11; moderate running: 1 h/day, 5 days/week for 12 weeks) rats were submitted to 45 min low-flow ischemia (15% of initial coronary flow (CF)) followed by 30 min reperfusion. Active tension (AT) and CF were recorded at baseline and after 1, 3, 5, 10, 15, 20, 25 and 30 min of reperfusion. Left ventricular protein carbonylation, and both heat-shock-protein 70 (HSP70) and endothelial nitric oxide synthase (eNOS) contents were determined by Oxyblotting and Western blotting, respectively. Regular physical exercise improves impairment of functional post-ischemic recovery (AT and CF) of aged hearts during reperfusion and this cardioprotection is associated to limited protein oxidation and increased HSP70 and eNOS myocardial contents.