DELAYED RADIATION EFFECTS IN ABDOMEN-IRRADIATED RATS.

Abstract

Two series of studies were conducted in adult male Sprague-Dawley rats exposed to x radiation, one involving exposure of the intact abdomen to 850 rads and the other, exposure of the abdomen exclusive of the gastrointestinal tract to 1300, 3500, or 5000 rads. In both cases, the head, forelegs, and thoracic area were shielded during irradiation. Abdomen-irradiated animals were divided into two groups one of which was treated with antibiotics. The most prominent observation in the abdomen-irradiated animals was the high incidence of tumors, and it was found that prior treatment with antibiotics had no apparent influence on either the pattern of delayed radiation mortality or tumorigenesis. Results in the abdomen-irradiated animals also suggest that an animal with a relatively high radioresistance to intestinal injury does not necessarily have a high resistance to delayed effects of radiation. Gastrointestinal tract shielding was found to increase the lifespan of animals abdominally irradiated. Gross and histological examinations were made to determine the possible cause of death in the gastrointestinal shielded irradiated rats, and the results strongly suggest the involvement of gross kidney pathology as one of the major causative factors in animals receiving 1300- and 3500-rad doses, but cause of death in animalsmore » of this group given 5000 rads was not readily apparent. (H.M.G.)« less