Stimulation of cell proliferation in rat liver by alpha-hexachlorocyclohexane or partial hepatectomy and end points during G1 of the inhibitory action of beta-diethyl-aminoethylphenyldiallyl acetate-HC1 (CFT 1201), beta-diethylaminoethyldiphenylpropyl acetate. HC1 (SKF 525-A) and actinomycin D.

The present work was designed to study the nature, sequence and temporal position of some inhibitor-sensitive events of the replicative cycle in rat liver. Hepatocyte proliferation was induced by alpha-hexachlorocyclohexane and by partial hepatectomy; the onset of DNA synthesis and of mitotic activity were determined and used as reference points in the cell cycle. Inhibition of cell proliferation was achieved by CFT 1201, SKF 525-A, and actinomycin D. It was found that the inhibitory action of the three agents ends at the same stage of the replicative cycle, 0--2 h before the G1/S transition, in both alpha-hexachlorocyclohexane-stimulated and regenerating rat liver. It is concluded that the molecular events sensitive to CFT 1201, SKF 525-A or actinomycin D are either identical or temporally closely associated; they do not figure in the metabolic activation of alpha-hexachlorocyclohexane.