The impairment of essential fatty acid metabolism as a key factor in doxorubicin-induced damage in cultured rat cardiomyocytes

The clinical use of the antitumoral doxorubicin (DOX) is limited by its cardiotoxicity, which is mediated through different mechanisms. The membrane lipid peroxidation induced by DOX may cause disruption of the unsaturated fatty acyl chains; in the endoplasmic reticulum, containing the system catalyzing the desaturation/elongation of fatty acids, DOX could interfere with the metabolism of linoleic and α-linolenic acids. Using primary cultures of neonatal rat cardiomyocytes we demonstrated that the exposure to different concentrations of DOX (10−5 and 10−7 M) for 24 h caused an increase in the production of conjugated dienes, an impairment in the desaturation/elongation of essential fatty acids, and a reduction in the cellular content of highly unsaturated fatty acids. Conversely, 1 h exposure to 10−5 M DOX was sufficient to induce alterations in the desaturation/elongation of linoleic and α-linolenic acids, but did not cause either formation of conjugated dienes or modification of the fatty acyl pattern. Therefore, DOX has a dual negative effect, depending on its concentration and on the time of exposure, one directed against the membrane highly unsaturated fatty acids, the other against the system which is required for the synthesis of these fatty acids themselves. These two effects synergically act in causing heart cell damage.