Differences in Survival of Mouse Colon Crypts after Whole- or Partial-body Irradiation

Summary

The survival of mouse colon crypts after X-irradiation has been studied by the microcolony technique. The D₀ for crypt survival was 266 rad after whole-body irradiation in air, but when the colon alone was irradiated, the D₀ was 340 rad. In mice which were breathing 95 per cent oxygen, the D₀ values were 238 rad for whole-body and 302 rad for colon irradiation. The survival curves were all extrapolated to the same number, and the D_Q was also increased with colon irradiation. There was, therefore an enhancement of colon crypt survival of about 27 per cent by local as opposed to whole-body irradiation. These results might be explained by a circulating repair promoter or by the production of a toxin after whole-body irradiation.