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The thiobarbituric acid (TBA) reaction method established by Yagi to determine the lipid peroxide level in serum and animal tissues was applied to isolated mitochondria with some modifications. The TBA reaction was carried out in acetic acid (pH 2.0) in the presence of 0.7 °o sodium dodecyl sulfate at 951CC for 45 min. Chloroform was used to remove the lipid and protein from the reaction mixture. An aqueous layer was used for spectrophotometric measurement at 532.5 nm to determine the TBA reaction product with lipid peroxide. To evaluate the TBA assay system, the lipid peroxide content of mitochondrial suspensions exposed to ultraviolet light was examined. The lipid peroxide formed in mitochondria was proportional to the dose of ultraviolet energy. The lipid peroxide of methyl linoleate exposed to ultraviolet light was determined both with the TBA reaction and with the hydroperoxide reaction. The linear increase in TBA values following UV exposure was similar to the increase of hydroperoxide values determined iodometrically. The TBA assay was shown to be a good predictor of lipid peroxide formed in mitochondria. This assay system is useful for lipid peroxide determination in various tissues: epidermis, Ehrlich ascites tumor cells and B-16 melanoma culture cells.

Summary: To determine the mechanism of adriamycin (ADR) induced cardiotoxicity, the effects of ADR on the Ca2+ uptake and release of cardiac mitochondria were investigated. Male Wistar rats were injected intraperitoneally with 4 mg/kg body weight of ADR for 6 consequtive days, and mitochondria were isolated from heart muscle. Ca2+ uptake and release of cardiac mitochondria were measured spectrophotometrically using a metallochromic dye antipyrylazo III. The total calcium content was determined by atomic absorption.ADR administration resulted in reductions of the Ca2T uptake velocity, Na+-Ca2+ exchange velocity and the calcium content in cardiac mitochondria.The data reported here is useful for understanding the pharmacological effect of adriamycin to unfavourable side-effect, cardiotoxicity.