[Characteristics of hepatocarcinogenesis after single exposure of synchronized cells of the regenerating liver to N-nitrosodiethylamine and subsequent administration of phenobarbital].

The frequency of tumour incidence in rats subjected to the single action of diethylnitrosamine to regenerating liver cells synchronized in different phases of the mitotic cycle was maximal in rats exposed to carcinogen when 62.5% of regenerating liver hepatocytes were in the S-phase. Dietary added phenobarbital increased the number and size of hepatocarcinomas especially in rats which received DENA in the G2-M phase of hepatocytes or during maximal proliferation of nonparenchymal cells. The role of proliferation of different cell populations in initiation and promotion of carcinogenesis is discussed.