Effects of seven anthracycline antibiotics on electrocardiogram and mitochondrial function of rat hearts.

Daunomycin, adriamycin and 5 semisynthetic anthracycline antibiotics inhibited oxygen consumption or ATP production of rat heart mitochondria in vitro. The no-effect levels varied depending on the substrate used and ranged from 1 nmole per mg mitochondrial protein. Mitochondrial functions were also studied in hearts of rats treated with repeated i.p. injections of the 7 antibiotics. Decrease in oxygen consumption without change in ATP production was observed with adriamycin and NSC-149584. Daunomycin, NSC-164011, NSC-143496 NSC-143114 affected primarily ATP production. The most potent compounds were daunomycin and adriamycin which damaged mitochondrial function at cummulative doses of approximately 10 mg/kg. ECGs were monitored in groups of equally treated rats. Cardiotoxicity manifested itself by progressive widening of the QRS complex often followed by the development of a S-wave trough. The most toxic compounds also induced intraventricular block, bradycardia and heart failure. The development of the ECG changes showed a good correlation with the impairment of mitochondrial function.