Proliferation kinetics and lethality after irradiation; modification by radioprotection.

By means of radioprotection, it was shown that a correlation exists after LD 50/30 between radiation-induced changes in cellular proliferation of critical radiosensitive tissue (bone marrow) and lethality, both in the time course and in the degree of the effect. Close correspondence between proliferation changes after irradiation and radiation lethality indicates that the inhibition of proliferation activity may play a major role in the mechanism of the death of irradiated organisms. A modification of cellular proliferation results in a change in radiation mortality.

Repair synthesis of DNA after irradiation and its modification due to radioprotection in vivo.

Repair DNA synthesis was examined in bone marrow cells exposed to LD 50/30 in vivo. Intensive repair synthesis took place during the irradiation, and the increase in 3HTdR uptake prevailed over the inhibitory effect of radiation and AET upon DNA synthesis. After LD 50/30, the intensity of DNA repair was reduced.