THE INTERRELATIONSHIP BETWEEN THALLIUM AND POTASSIUM IN ANIMALS

The relationship between the level of dietary potassium and the excretion of thallium was studied in rats and dogs. It was found that the disappearance of thallium from animals was a first order rate process. The rate of disappearance of thallium from animals increased as the level of dietary potassium increased. The increased rate of disappearance resulted primarily from an increased rate of excretion of thallium in the urine with no significant increase in the rate of fecal excretion. In dogs, the infusion of potassium increased the renal clearance of thallium and increased the mobilization of thallium from tissues. The rate of thallium excretion is reduced in adrenalectomized rats. Administration of deoxycorticosterone acetate (DOCA) increases the renal clearance of thallium in adrenalectomized dogs. The secretion of thallium in the saliva of sheep is also increased by the administration of DOCA. A comparison of the plasma disappearance of TI 204 and K 42 and of the uptake of these ions by tissue suggests that the ionic movements of thallium and potassium ions are related. Once inside the cell, thallium is less readily released than potassium. Activation of Na-and K-activated adenosine triphosphatase by the substitution of thallium for potassium supports the belief that the mechanism involved in the active transport of potassium cannot differentiate between thallium and potassium. The LD5O of thallium increased when the potassium intake was increased in rats. This suggests that potassium induced a translocation of thallium away from the toxic receptor site.