A Study of the Phases of Radiation Response in the Rat I. The Effects of Uniform Whole Body Irradiation

Abstract

Most rats show an appreciable wt. loss in the first day or so after X-irradiation with 400 r. This is followed by a recovery phase with re-establishment of the original growth rate until about the 12th day, when a 2d period of wt. loss may start abruptly. The wt. loss in both the 1st and 2d period of radiation response is attributed mainly to reduction in food intake. Generalized infection is not observed in either period of wt. loss. The 2d wt. drop is associated generally with severe anemia. There is no correlation between the severity of the wt. loss in either period and the extent of lymphopenia and granulocytopenia. Seven days after injn. of radioactive Fe rats were given 450 r and sacrificed during the 2d wt. drop (12 to 16 days after irradiation). Activity present in the liver, spleen, lymph nodes and excreta of the irradiated rats is considerably greater than in controls. The results indicate that gross hemorrhage is not the only factor in the production of the anemia. The admn. of beta-mercapto-ethylamine (cysteine amine) prior to irradiation reduces the initial wt. drop and the severity of the anemia.