A primary hepatocyte culture was used as a model system to assess the toxicity of various chemical substances. Chemical substances tested in this experiment included 14 kinds of organic solvents, arsenic acid and N-nitrosodiumethylamine, most of which are known as hepatotoxic materials. Enzyme (GPT and LDH) leakage and albumin secreted from the hepatocytes to culture medium were measured to evaluate the cell damage after exposure to the chemical substances at various concentrations for 3d. Cell counts and protein contents before and after exposure to the chemical substances were also measured during the course of these experiments. The extent of LDH leakge from hepatocytes was parallel to that of GPT leakage after exposure to the chemicals. Albumin secreted from the hepatocytes in the culture medium evidently decreased at concentrations of the chemicals which increased the enzyme leakage. Viable cell counts were significantly decreased by chemicals that increased the enzyme leakage, although the cell protein contents were not significantly affected.
The minimum concentration of the chemicals at which enzyme leakage from hepatocytes was significantly increased was defined as the lowest toxic concentration (TCL₀). Judging from TCL₀ values, the degree of toxicity in these chemicals seems to be almost identical to the degree of in vivo hepatotoxicity reported previously. We, furthermore, observed that there is a positive correlation (r=0.780, p<0.01) between PT₅₀ calculated by the LD₅₀ value reported previously and -Log|TCL₀|. These results indicate that the cultured rat hepatocytes can be applied to the selection test for hepatotoxic materials and also to short-term toxicity assessment of chemicals which affect liver function.