Effect of doxorubicin-enhanced hydrogen peroxide and hydroxyl radical formation on calcium sequestration by cardiac sarcoplasmic reticulum.

This study investigated the effect of doxorubicin-related oxygen radical formation on Ca2+ uptake by rat heart sarcoplasmic reticulum vesicles. Enzymatic activation of doxorubicin by cardiac NADH dehydrogenase produced a dose-related inhibition of Ca2+ uptake that was enzyme- and cofactor-dependent and that was inhibited by catalase, various hydroxyl radical scavengers, and the iron chelator deferoxamine. Furthermore, inhibition of Ca2+ uptake paralleled the production of the hydroxyl radical by NADH dehydrogenase after doxorubicin treatment. These results suggest that doxorubicin-stimulated reactive oxygen metabolism can alter Ca2+ transport by cardiac sarcoplasmic reticulum and may represent one pathway involved in the cardiac toxicity of this potent antineoplastic agent.