Influence of Chronic Gamma-irradiation on the Yield of Chromosomal Aberrations in Rat Liver Cells

The Cause of Attenuation of the Radiation Genetic Effect in Man as Compared to Mouse and Drosophila

“…It is worth mentioning here that as long ago as in 1963 we have described the attenuating effect of prolonged γ -radiation with respect to somatic mutagenesis [3,4], namely, the frequency of chromosomal aberrations reduced in regenerating liver cells of chronically treated rats after hepatectomy as compared to the same parameter after acute irradiation with the same total dose absorbed. Thus, in animals that underwent chronic γ -radiation at a total dose of 1.5 Gy but at various dose rates (from 0.0083 to 0.1 Gy per day; radiation duration, 180 to 15 days, respectively), the yield of chromosomal aberrations per regenerating liver cell diminished significantly as dose rate decreased; at the lowest radiation intensity, the number of aberrant cells was close to that in the control unirradiated animals of the same age.…”

“…Thus, in animals that underwent chronic γ -radiation at a total dose of 1.5 Gy but at various dose rates (from 0.0083 to 0.1 Gy per day; radiation duration, 180 to 15 days, respectively), the yield of chromosomal aberrations per regenerating liver cell diminished significantly as dose rate decreased; at the lowest radiation intensity, the number of aberrant cells was close to that in the control unirradiated animals of the same age. Even at that time, we assumed that chromosome damages are repaired under the conditions of chronic irradiation [3,4]. The possibility of repair of radiationinduced genome damage is now generally recognized [5,6].…”