Combined action of chronic and acute gamma-irradiations on the frequency of chromosome aberrations in bone marrow cells of rats

The adaptive response (AR) induced by low doses of ionizing radiation has been established for plants, human cells in culture, and whole animals. The adapting dose (AD) in these experiments was either a single or repeated low dose of ionizing radiation. Only in some works did the authors use chronic pre-irradiation. The purpose of the present work was to study the influence of chronic pre-irradiation on chromosome damage formation after after subsequent acute gamma-irradiation in vivo. We suggest that the capacity for AR on long-term whole-body irradiation of animals at a low dose rate will be higher than in vitro. Thus, from the presented data it can be concluded that the AD of chronic whole-body irradiation of rats with subsequent acute dose of gamma-irradiation induces an adaptive cytogenetic response at the organism level. The obtained results indicate that radio-adaptation can be induced in the range of cumulative doses of chronic pre-irradiation between 0.03 and 0.4 Gy at a dose rate of 0.0013 Gy/min. (authors)