Isolated hepatocytes from male rats were cultured in primary cell culture in 24-well dishes for 20–24 hours in the presence of the various test compounds. Cytotoxicity at the end of the culture period was evaluated by the determination of LDH-release into the culture medium or by quantification of DNA content as a measure of the cell number in each well. Toxic xenobiotics, such as chlorpromazine, were able to induce LDH-release at up to 5 times the background levels at concentrations of 10-4–10-5 M. For most compounds, the increase in LDH-release was closely related to a decrease in cell number, as measured by the DNA method. Two culture conditions which might influence the cytotoxic response were investigated. Prolongation of the culture time increased the toxicity of some compounds, e.g. sodium dodecylsulphate, whereas for other compounds, e.g. amitriptyline, no change was noted. Addition of serum albumin and α1-acid glycoprotein decreased the toxicity of chlorpromazine to isolated hepatocytes. These results indicate that isolated hepatocytes might represent a useful in vitro toxicity screening system, and that careful standardisation of the culture conditions is necessary.
Use of high-throughput in vitro toxicity screening data in cancer hazard evaluations by IARC Monograph Working Groups
