Hypothermia and Increased Survival Rate of Infant Mice Irradiated With X-Rays

Abstract

The survival of infant mice irradiated while in a state of extreme hypothermia (about 5[degree]C) is almost twice that of litter mates exposed to the same doses of total body X-rays at room temp. The mortality rate was not affected in infant animals less severely chilled, nor in adult mice chilled after being anesthetized. The protection afforded by extreme chilling was of about the same degree as that produced by placing the animals in a N2 atmosphere; furthermore, combining anoxia with refrigeration did not enhance the radiation protection. The benefit derived from extreme chilling was less if animals were placed in pure O2 rather than in N2. It is concluded that lowered tissue O2 played an important role in increasing the survival rate of chilled infant mice.