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In an attempt to evaluate the cytotoxicity of adriamycin, an anticancer drug, colorimetric assays of neutral red(NR), tetrazolium MTT, lactate dehydrogenase activity and protein content were investigated on myocardial and endothelial cells from the newborn rat heart grown for 96 hours in media containing adriamycin of various concentrations. Light and electron microscopic studies were also carried out on these cells. Initial and midpoint cytotoxicities of adriamycin in myocardial cells were detected at lower concentrations in the NR assay(NR-90, 0.07 ㎍/ml ; NR-50, 2.0㎍/ml) than in the MTT assay (MTT-90, 0.15㎍/ml ; MTT-50, 2.8㎍/ml). However, in endothelial cells, they were noted to be at lower concentrations in the MTT assay(MTT-90, 0.1㎍/ml ; MTT-50, 2.3㎍/ml) than in the NR assay (NR-90, 0.3㎍/ml ; NR-50, 4.1㎍/ml). Protein content in myocardial cells treated with adriamycin, NR-50 and MTT-50 were calculated to be 38.1 % and 34.1 % to the control respectively and these in endothelial cells grown in media containing adriamycin, NR-50 and MTT-50 were 36.4% and 45.7 % to the control respectively. With addition of adriamycin, increase in amount of LDH was noted in media of both myocardial and endothelial cells and was dose-dependent of adriamycin. In light microscopy, both myocardial and endothelial cells were observed to decrease in number and shape of these cells became more spherical than that of the control with adriamycin treatment. Electron microscopy of adriamycin treated cells showed increment of lysosome and vacuoles, swelling of mitochondria and cisternal dilatation of rough endoplasmic reticulum. These results suggest that adriamycin inhibits in vitro proliferation and growth of the cells by disturbing the cell metabolism.
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