The induction of ornithine decarboxylase and DNA synthesis in rat hepatocytes after a single administration of diethylnitrosamine.

In primary monolayer culture of adult rat liver cells, the presence of a mixture of hormones stimulates DNA synthesis and proliferation. Under conditions of suboptimal hormone stimulation diethylnitrosamine was found to be effective in stimulation of DNA synthesis. Diethylnitrosamine also influences ornithine decarboxylase activity. The effect of some carcinogens and their structural related non-carcinogenic analogs on ornithine decarboxylase activity in primary cultured rat hepatocytes was studied. The addition of the carcinogens diethylnitrosamine, benzo[a]pyrene, methylmethanesulphonate and ethylmethanesulphonate caused significant increases in ornithine decarboxylase activity. Under the same conditions the non-carcinogenic analogs diethylformamide and pyrene did not show this change in enzyme activity.