Dose Reduction Factor for Radiation Lethality in Mice as a Function of the Dose of Mercaptoethylamine

Dose reduction factors (DRF) were determined for various doses of mercaptoethylamine (MEA) administered either intravenously or intraperitoneally to mice before whole body x-irradiation. MEA doses ranging from 125 to 600 mg/kg were administered intravenously while MEA doses as high as 750 and 900 mg/kg were administered intraperitoneally. The toxicity of MEA was greater in mice kept at 30°C than in those kept at 22°C. The detoxification rate for MEA was about 90 mg/kg/hour. Pentobarbital administration, either in a single or in multiple injections, after irradiation and control of environmental temperature were used to counteract the toxicity following high doses of MEA. The acute mortality rate after large doses of MEA was high. The DRF values were approximately proportional to the MEA dose up to 600 mg/kg. The highest DRF (2.81) was obtained with an intravenous MEA dose of 600 mg/kg.