Adriamycin-induced lipid peroxidation in mitochondria and microsomes

Abstract

The effect of the anti-neoplastic agent adriamycin on the peroxidation of lipids from rat liver and heart mitochondria and rat liver microsomes was investigated. The extent of total lipid peroxidation was determined by assaying for malondialdehyde (MDA), while the degradation of unsaturated fatty acids was monitored using gas chromatography. For liver mitochondria and microsomes, the formation of MDA was dependent on the concentrations of adriamycin, Fe 3+, and protein, as well as time. In the presence of 50 μM adriamycin and saturating amounts of NADH, 1.5 ± 0.2 nmol MDA/mg protein/ 60 min was produced with liver mitochondria. Upon addition of 25 μM Fe 3+, the amount of MDA generated was increased to 6.5 ± 0.1 nmol/mg protein/60 min. Liver microsomes produced amounts which were approximately 2-fold higher under all conditions. No MDA formation could be detected in rat heart mitochondria. The addition of 50 μM chlorpromazine completely inhibited peroxidation, whereas 0.5 to 1.0 mM p-bromophenacyl bromide blocked MDA formation by 50%. Analysis of fatty acids by gas chromatography showed that there was about a 50% decrease in arachidonic and docosahexaenoic acids in liver mitochondria and microsomes, but no change in the fatty acid content of heart mitochondria when incubated with both 50 μM adriamycin and 25 μM Fe 3+ for 1 hr. These results suggest that (1) therapeutic concentrations of adriamycin enhance the peroxidation of lipids in liver mitochondria and microsomes through an enzymatic mechanism, especially in the presence of Fe 3+; and (2) toxicity of this drug may be related to the degradation of membrane lipids.