Acid-Base Balance in the Dog Following X-Irradiation

The acid-base balance of 22 adult, female, uninephrectomized dogs was studied prior to and for 11 days following exposure to 400 R total body x-irradiation. Acid-base balance was evaluated by simultaneously measuring renal net acid excretion, apparent metabolic acid production, and body fluid acid-base changes. The first 6 days following irradiation, net acid excretion was significantly elevated and apparent metabolic acid production appeared to increase. Whole body intracellular pH was significantly elevated on the 5th day postirradiation, suggesting a movement of acid from the intracellular space to the urine during this time. During the last 5 days a compensated metabolic acidosis was present in the extracellular fluid, while the whole body intracellular pH was decreased on the 11th day postirradiation. Acid excretion tended to decrease while apparent metabolic acid production returned to control levels. The development of acidosis at this time, without an increase in acid excretion, suggests an alteration in renal acid-base regulation.