Disruption of mitochondrial calcium homeostasis following chronic doxorubicin administration
Abstract
Doxorubicin (Adriamycin) is an anthracycline antibiotic with broad antineoplastic activity. However, the clinical success is limited by the incidence of cumulative cardiomyopathy. In vitro, doxorubicin elicits a cyclosporine A-sensitive release of calcium from cardiac mitochondria. It has been suggested that this leads to mitochondrial calcium cycling and depolarization of membrane potential, which may account for the inhibition of mitochondrial respiration and cytotoxicity observed with the drug. Implication of a similar mechanism in the manifestation of clinical doxorubicin toxicity requires evidence for a disruption of mitochondrial calcium homeostasis following chronic in vivo administration. Cardiac mitochondria isolated from doxorubicin-treated rats (2 mg/kg/week, s.c. x 13 weeks) had a lower RCR but no change in ADP/O compared to controls and exhibited an enhanced cyclosporine A-sensitive release of mitochondrial calcium. Associated with this was a calcium-induced depolarization of membrane potential, which was inhibited by either cyclosporine A or ruthenium red suggesting the induction of mitochondrial calcium cycling following chronic doxorubicin treatment. The persistence of these effects on mitochondrial calcium regu...Continue Reading
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