Survival Studies of Whole-Body X-Irradiated Germfree (Axenic) Mice

Abstract

The response of germfree (axenic) Swiss-Webster mice to whole-body X-irradiation in the range of 500 to 3000 r was compared to that of conventional Swiss-Webster mice. The LD50(30) dose for axenic mice was 705 r, and that for conventional mice was 660 r. The slopes of the dose-response curves were the same. However, the survival times at a given dose were markedly different. On a log-log scale the relationship between dose and survival time is linear, the 650 r to 3000 r range producing mean survival times from 15 to 7 days. The survival time of conventional mice is about 4 days less than for axenic mice in the 500 r to 1000 r range and then drops sharply to a plateau of between 3 and 4 days.