[The influence of the rhythm of the damaging agent on the character of hepatic reparative regeneration].

The effect of frequency of administration of tetrachloride of carbon (CCl4) on synthesis of DNA by hepacytes and cells of the stroma, as well as on composition and magnitude of infiltrates in the liver of mice was studied. For this purpose autoradiographic and histological studies of the liver tissue in animals injected with poison once a week, twice a week and every day were carried out dayly. Periodic increases in number of hepacytes tagged with thymidin-H3 and an increase in the number of cells in infiltrates were observed. The rhythm of these changes corresponded to the frequency of administration of CCl4. With the rise in the frequency of injections of the poison the rate of increase in number of cells in infiltrates rose and synthesis of DNA in hepacytes became more intensive. The time interval, however, between the injection of the toxin and the rise of DNA synthesis in hepacytes remained constant irrespective of the frequency of exposure to the damaging factor.