The Time-Intensity Relations of Whole-Body Acute X-Irradiation and Protection by β-Mercaptoethylamine

Abstract

CF1 male mice of the same age and weight were exposed between parallel beams of X-rays at 365 r/min. or 1500 r/min. In the first experiments mice were X-irradiated to death which occurred in 85 minutes after 125,000 r at 1500 r/min. or in 3 hours after 66,000 r at 365 r/min. In further experiments, mice were exposed to 66,000 r at the faster rate of 1500 r/min. and survived for some 8 to 10 hours. At the faster rate of exposure to death there may be some biologically ineffective (wasted) radiation. When beta-mercapto-ethylamine is injected intraperitoneally prior to X-irradiation-to-death, at either rate of exposure, the mice die more quickly than do the controls. If the injection is made after irradiation has begun, the mice die even earlier. Thus there is no evidence of protection by this drug under acute radiation-to-death conditions. If mice are injected prior to administration of 66,000 r at the faster rate of 1500 r/min., they tend to live longer (i.e., 20 hours), indicative of some protection. Post-irradiation injection of beta-mercaptoethylamine was deleterious in all instances.