Relation of anterior pituitary function to aldosterone secretion in conscious dogs.

Abstract

Secretion of aldosterone and corticosterone was studied in conscious dogs by means of a chronic indwelling catheter to obtain adrenal vein blood. In most conscious normal dogs, steroid secretion was lower than in anesthetized normal animals following acute adrenolumber vein cannulation. However, in dogs not well trained or excitable, secretion of aldosterone and corticosterone was strikingly elevated above the basal output. This finding probably reflects an increased plasma level of ACTH. In dogs with thoracic caval constriction, aldosterone output was markedly increased above normal whereas corticosterone and Porter Silber chromogen secretion was frequently very low, a finding which suggests a normal plasma level of ACTH. Hypophysectomy of dogs with caval constriction resulted in a greater, more abrupt fall in corticosterone than in aldosterone secretion. In two of these dogs, aldosterone secretion fell to normal or below within 2 days, whereas in the other two dogs, aldosterone output, although reduced, remained above normal for several days. Porter Silber chromogens showed changes similar to those observed for corticosterone. It is concluded that the anterior pituitary provided important support for increased aldosterone production but was unessential for hypersecretion of aldosterone.