Gastrointestinal Function during Exposure to X-Rays

Abstract

Transfer of intubated material can be used as a quantitative measure of gastric transit in rats over short periods of time. The data are consistent with the hypothesis that gastric transit over short periods of time is an exponential decay type of process. Exposure to radiation throughout the transit interval decreases the rate of transit in intact animals by a factor of at least 3, with no latent period or minimum effective dose involved. Gastric motility is depressed and may play a role in decreasing the rate of gastric transit during radiation exposure. In adrenalectomized animals, gastric transit is much more rapid than in normal animals, and irradiation throughout the transit interval results in little or no decrease in the rate of gastric transit. It is suggested that adrenal action is important for the radiation-induced delay in gastric transit as measured by this technique. Transit of test material through the small intestine also appears to follow an exponential type of process, moving most rapidly at the pyloric end, and least rapidly as the cecum is approached. In contrast to gastric transit, however, intestinal transit during exposure to ionizing radiation appears to proceed at a rate indistinguishable from that observed in nonirradiated control animals.