Protective effects of carvedilol against doxorubicin-induced cardiomyopathy in rats.

Carvedilol (CAR) is a vasodilating beta-blocker which also has antioxidant properties. CAR produces dose-related reduction in mortality in patients with congestive heart failure. In the present study, we tested the hypothesis that CAR protects against doxorubicin (DOX)-induced cardiomyopathy in rats. Sprague-Dawley rats were treated with DOX, CAR, CAR+DOX, or atenolol (ATN)+DOX. DOX (cumulative dose, 15 mg/kg) was administered intraperitoneally, and CAR (30 mg/kg daily) or ATN (150 mg/kg daily) was administered orally. Three weeks after the completion of these treatments, cardiac performance and myocardial lipid peroxidation were assessed. Mortality was observed in the DOX (25%) and ATN+DOX (12.5%) groups. Compared with control rats, DOX significantly decreased systolic blood pressure (104+/-4 vs. 120+/-4 mmHg, P<0.05) and left ventricular fractional shortening (38.8+/-3.1 vs. 55.4+/-1.3%, P<0.01), and resulted in a significant accumulation of ascites (14.4+/-4.9 vs. 0 ml, P<0.01). CAR significantly prevented the cardiomyopathic changes caused by DOX, while ATN did not. The myocardial thiobarbituric acid reactive substances (TBARS) content was significantly higher in DOX-treated rats than in control rats (80.4+/-7.1 vs. 51.5+/-1.2 nmol/g heart, p<0.01). CAR prevented the increase in TBARS content (48.8+/-3.0 nmol/g heart, P<0.01 vs. DOX group), whereas ATN had no significant effect (74.3+/-5.2 nmol/g heart). CAR also significantly prevented the increase in both myocardial and plasma cholesterol concentrations caused by DOX. These data indicate that CAR protects against DOX-induced cardiomyopathy and that this effect may be attributed to the antioxidant and lipid-lowering properties of CAR, not to its beta-blocking property.