[The efficacy of gammaphos in whole-body irradiation during normal oxygenation and hypoxia].

The authors showed the absence of differences in the value of a protective effect of gammaphos at doses of 0.25 and 0.5 mM/kg (67 and 134 mg/kg) evaluated by the survival of mice irradiated in the air and while breathing a gaseous mixture containing 10% O2; the dose modifying factor (DMF) was 1.15 and approximately equal to 1.3, respectively. During irradiation of mice under conditions of normal oxygenation and while breathing hypoxic gaseous mixtures containing 10 and 8% O2 no differences were found in the level of an antiradiation effect of gammaphos at a dose of 1mM/kg (268 mg/kg); the DMF of gammaphos in all the cases was 1.6. During a short-term hard hypoxia (6.5% O2, DMF = 2.01), the protective effect of gammaphos is somewhat lower (DMF = 1.41) perhaps as a result of the modification limits in radiosensitivity because the DMF in the combination of both factors (gammaphos + 1 min. of 6.5% O2) equals 2.84. The DMF of gammaphos under the conditions of 20 min hypoxia (6.5% O2) producing a lesser radioprotective effect (DMF-1.48) equals 1.6, i. e. the value of the gammaphos protective effect in this case does not differ from that during irradiation of mice in the air. The data obtained lead to a conclusion of the independence of the value of the gammaphos protective effect on the level of the oxygenation of cells and tissues of irradiated objects.