Magnesium protection against anthracycline toxicity in vitro.

The clinical usefulness of the antitumour agents daunomycin (DAU) and adriamycin (ADR) is limited by their secondary cardiotoxicity. The anthracycline compounds have a number of detrimental effects on the biochemical and morphological integrity of the cardiac cell which may be related to the accumulation of cellular calcium. Using a model of spontaneously beating, cultured neonatal rat cardiomyocytes, we examined the cardioprotective role of magnesium during 2 hours of exposure to 10, 25 or 50 micrograms/ml DAU. A significant preservation of myocyte membrane integrity and cellular morphology was observed with the addition of equimolar magnesium. Magnesium opposes the actions of calcium in a number of tissues and it may be this calcium antagonist action that makes magnesium effective in DAU toxicity.