[Changes in liver histones in rats after single, continuous and combined irradiation with gamma rays].

The authors examined the concentration and total contents of histones and the relative ratio of different fractions of histones in the liver of rats after a single (6 Gy), continuous (total dose 1.4 Gy cumulated at rate of 0.1 Gy per day) and combined continuous and single irradiation with gamma rays. The most extensive changes of histones were revealed after combination of continuous and single irradiation. Continuous irradiation did not lead to activation of reparative mechanisms which would mitigate the response to the subsequent single irradiation. The summation of effects is apparent from the fact that in the liver, contrary to organs with active cellular proliferation, irradiation with small doses does not increase the resistance to the subsequent irradiation, on the contrary, cumulation of damage was observed.