Cell Proliferation in the Regenerating Liver and the Effect of Prior Continuous Irradiation

• Published in: Radiation research 1967-12, Vol.32 (4), p.804-826
• Main Author: Fabrikant, Jacob I.
• Format: Article
• Language: English
• Subjects: Animals; Autoradiography; Cell growth; Chromosome aberrations; Chromosome Aberrations - radiation effects; DNA - biosynthesis; Hepatectomy; Hepatocytes; Irradiation; Kinetics; Liver; Liver cells; Liver Regeneration - radiation effects; Male; Mitosis; Mitosis - radiation effects; Radiation damage; Radiation dosage; Radiation Genetics; Radiation Injuries, Experimental; Rats; Thymidine - metabolism; Tritium
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3572288

The effect of prior continuous irradiation was studied (1) at 47 rads/day for 15 days and 30 days on the patterns of proliferation of parenchymal and littoral cells in the rat liver after partial hepatectomy, and (2) at 47 rads/day for 15 days on the S and${\rm G}_{2}+{\rm M}/2$phases of proliferating parenchymal cells during regeneration, and for periods up to 120 days on the production of observable chromosome injury in proliferating hepatocytes. Following continuous exposure and the accumulation of large doses, cell proliferation could be initiated and maintained, albeit at a reduced rate, despite large numbers of radiation-induced chromosome aberrations. Changes in the patterns of DNA synthesis and cell division following irradiation included altered timing with a delay in the onset of synthesis and mitosis, a decrease in the rate of entry of cells into synthesis and division, a decrease in the numbers of cells taking part in the regenerative process, and an increase in the overall period of cell proliferation. There was a slight shortening of the duration of S phase, and possibly a greater variation in the duration of the${\rm G}_{2}+{\rm M}/2$complex phase, probably accompanied by cells held up in passage through this period. The number of radiation-induced chromosome aberrations was dependent on the duration of exposure and accumulated dose. Reduction of chromosome aberrations was not apparent after a 10-day radiation-free interval prior to partial hepatectomy. Despite the accumulation of the radiation damage, viable cells in the regenerating liver remnant divided a few times to replace a very large proportion of the parenchymal and littoral cell population deficits within the short period of 1 week.