Chemical protection against the long term effects of a single whole body exposure of mice to ionizing radiation. I. Life shortening

A systematic study has been made of the advantage gained by treatment with combined radiochemical protectors for long-term survival of mice exposed to a single dose of ionizing radiation. Our results demonstrate that mixtures of radioprotectors increase the degree of protection compared with that obtained with each substance given separately. The dose-effect curves for the long-term survival obtained for irradiated untreated mice and for mice treated with a mixture of radioprotectors are not parallel. Thus the dose-reduction factor (DRF) varies with the X-ray dose administered. The optimum DRF obtainef for long-term survival of BALB/c⁺ mice (2.5) was very close to that obtained against acute effects of ionizing radiation (2.8).