Electrolyte Excretion in the Rat after Severe Intestinal Damage by X-Irradiation

Abstract

The study of radiation dose-survival relationships in several species of laboratory animals has led to the identification of a specific lethal syndrome characterized by within 3 to 5 days and associated with exposure of the tract (1-4). A striking feature of this syndrome is the development of severe diarrhea which suggests rapid and excessive loss of water and electrolytes, a factor which has been considered as a possible cause of intestinal radiation death (5). It is of interest, therefore, to investigate electrolyte excretion in animals exhibiting this syndrome and to attempt to correlate alteration of electrolyte metabolism with radiation-induced mortality. Considerable information is already available which indicates that there are substantial changes in electrolyte metabolism after X-irradiation (6-11). Some investigators (6, 7, 9) noted altered urinary and fecal excretion of electrolytes in irradiated animals, but the radiation doses were too low to cause intestinal radiation Other workers (8, 10) used high doses; however, fecal excretion of electrolytes was not studied. In the present study fecal and urinary excretions of sodium, potassium, and water were studied in fasting rats subjected to 1500 r whole-body X-irradiation, a dose sufficient to cause severe damage and early death. Fasting animals were used, since food intake is markedly reduced (12) and absorption is altered (11, 13, 14) after irradiation of the rat. The study also includes a comparison of the sodium loss incurred by the fasted irradiated rat with the amount of sodium removal (by means of intraperitoneal dialysis) which produces in the fasted nonirradiated rat.