Cardioprotection During Ischemia-Reperfusion By Endurance Training In Senescent Heart

Vulnerability to ischemic cardiac diseases increases with age. In adult rat heart, chronic exercise provides cardioprotection against ischemia-reperfusion (I/R) injury by mechanisms involving oxidative stress, HSPs and NOS pathways. To determine if endurance training is able to induce cardioprotection in senescent heart and to investigate the involved mechanisms. 24 month old (mo) male Wistar rats underwent 12 weeks of mild treadmill running (16 m/min; 5% grade; 1h/day, 5 days/week, 70% VO2max) and were compared to sedentary 4 and 24 mo rats. After sacrifice 48 h after the last exercise, isolated hearts were submitted to 45 min of low-flow ischemia (15% of initial coronary flow (CF)) followed by 30 min of reperfusion and coronary perfusion and contractile function were recorded at baseline and 1, 3 and 30 min of reperfusion. Then, HSP70 and eNOS protein contents and protein carbonylation were quantitated in left ventricle. Citrate synthase activity increased in 24 mo trained soleus (vs 24 mo sedentary) indicating efficient endurance training. Training improved the post-ischemic vasodilation response as soon as the 1st min of reperfusion and fully prevented impairment of CF after 30 min in 24 mo hearts (Table). This training effect on coronary vasoconstriction was also associated with increased post-ischemic recovery of contractile function.Training also limited protein oxidation and increased HSP70 and eNOS myocardial contents after I/R in 24 mo hearts (Table). Endurance training induces cardioprotection in senescent heart mainly by preventing early coronary vasoconstriction during reperfusion. Mechanisms involved are oxidative stress, HSP and NOS pathways, previously identified as targets of protective effect of endurance training in adult heart. This particular success of training in cardioprotection after I/R in senescent rodent encourages aged people to practice regular physical activity.