Exercise training attenuates acute doxorubicin-induced cardiac dysfunction

The use of doxorubicin, a highly effective antitumor antibiotic, is limited by a dose-dependent cardiotoxicity. The purpose of this study was to determine whether chronic exercise training (ET) prior to doxorubicin treatment would preserve cardiac function and reduce myocardial oxidative stress following treatment. Rats were exercise trained on a motorized treadmill or confined to sedentary cage activity for 12 weeks, then administered all intraperitoneal injection of doxorubicin (15 mg/kg) or 0.9% saline. Five days following the injections, hearts were isolated and Langendorf perfused to assess cardiac function and then processed for biochemical analyses. Doxorubicin treatment induced significant inotropic, lusitropic, and chronotropic cardiac dysfunction, reduced coronary flow, and increased cardiac lipid peroxidation in the sedentary animals. Doxorubicin treatment was also associated,with a decrease in cardiac manganese superoxide dismutase protein expression and an increase in heat shock protein-72 (Hsp72) compared with saline-treated animals. Exercise training attenuated doxorlibicin-induced cardiac dysfunction, and lipid peroxidation, and led to a greater cardiac expression of Hsp72 compared with the sedentary animals. The results of this study demonstrate for the first time that chronic exercise training before doxorubicin treatment protects against cardiac dysfunction following treatment, and provide evidence for a sustained increase in myocardial Hsp72 following exercise training and doxorubicin treatment in vivo.