Evidence for Secretion of an Aldosterone-stimulating

In an earlier report (1), it was suggested from cross circulation experiments that a humoral agent provides the immediate stimulus for aldosterone production. It was proposed that this humoral substance be called the aldosterone-stimulating hormone (ASH). The present experiments were designed to determine the locus of secretion of ASH. Specific regions or organs which might be the source of ASH were removed and, subsequently, attempts were made to stimulate aldosterone secretion by bleeding. A positive response to bleeding in the absence of ACTH has been considered as presumptive evidence for secretion of ASH. It is important that studies be conducted in hypophysectomized dogs since bleeding (2, 3) stimulates release of ACTH which promotes increased aldosterone secretion. Bleeding was used as a stimulus because it is a simple and effective means of increasing aldosterone production. Studies were made in normal dogs to establish the magnitude of the response in aldosterone secretion to bleeding. In view of the marked fall in aldosterone secretion following hypophysectomy, the possibility was examined that ASH is secreted by the anterior pituitary. Since a response in aldosterone secretion to acute blood loss was obtained in hypophysectomized dogs, the effects of decapitation and subsequent bleeding were next determined. Finally, the effects of bleeding on aldosterone secretion were observed in hepatectomized-hypophysectomized dogs and in nephrectomized-hypophysectomized animals, and