THE PRIMARY ACTION OF THE PARATHYROID HORMONE1

Abstract

Parathyroid extracts produced no effect on the serum Ca in rats, cats or dogs immediately following nephrectomy or ligation of the renal vessels or of the ureters. Reestablishment of urine flow in one cat by cutting the ligated ureters was followed by a normal parathyroid hypercalcemia. During anuria induced by post. pituitary extract no parathyroid hypercalcemia was noted. Inj. of parathyroid extract followed by repeated intravenous adms. of Na acid phosphate to maintain a constant serum phosphate level prevented the customary rise of serum Ca. The evidence given does not suggest a direct effect of the parathyroid hormone on bone. These results rather favor the theory that the primary action of the parathyroid hormone is upon the excretion of phosphate by the kidney.