The Role of Parathyroid Hormone and Thyrocalcitonin in Altering Plasma Calcium Levels and Adrenocortical Secretory Rates[*]

Abstract

The intravenous infusion of parathyroid hormone markedly increased both plasma calcium levels and the secretion of steroids by the adrenal cortex of intact anesthetized dogs. Thyrocalcitonin did not affect adrenocortical secretory rates while significantly depressing the levels of plasma calcium. The adrenocortical response to parathyroid hormone administration was abolished by hypophysectomy indicating that the elevated plasma calcium levels act on the hypothalamohypophyseal system causing the release of adrenocorticotropin. These findings suggest that the feedback mechanisms for calcium regulation and adrenocortical steroid secretion may be interrelated.

Key words

Plasma Calcium - Adrenocortical Secretion - Parathyroid Hormone - Thyrocalcitonin

1 Supported in part by internal grants of the University of Illinois and the Office of Naval Research Contract NR 101-580. The author is indebted to L. Goffman, C. Lau and W. Machaj for their excellent technical assistance and to Greyhound(formerly Armour) Pharmaceutical Co. for the generous supply of thyrocalcitonin.

1 Supported in part by internal grants of the University of Illinois and the Office of Naval Research Contract NR 101-580. The author is indebted to L. Goffman, C. Lau and W. Machaj for their excellent technical assistance and to Greyhound(formerly Armour) Pharmaceutical Co. for the generous supply of thyrocalcitonin.