Influence of Hypothermia on the Survival of Mice after Large Doses of X-Radiation

Abstract

IT is known that hypothermia applied after irradiation prolongs the survival of frogs^1,2 and hibernating animals³, and slows down destructive processes in the hæmatopoietic tissue and blood^3,4. In our previous work we showed that prolonged hypothermia at 22–25° C., lasting 6–48 hr., after irradiation also slows down destructive changes in the blood, spleen and bone marrow^5,6. After the ending of hypothermia and reaching the normal body temperature these changes, however, develop even more intensely than in controls subjected to irradiation only and the mean survival-time is shorter. After doses up to 15,000 r. animals survive for more than 3 days after irradiation⁷ and do not tolerate such prolonged hypothermia. Therefore investigations of the survival-time after irradiation in homoiothermic animals under hypothermia can be carried out only after large doses of irradiation where the control animals die a few hours following irradiation, which is a well-tolerated duration of hypothermia.