Vasopressin and ACTH Release

Abstract
Summary A new method of testing for ACTH-releasing activity of neurohumoral substances has been described. The material to be tested is injected directly into the arterial blood supply of an ACTH-secreting pituitary tumor grafted in the hind leg of a hypophysectomized rat. The amount of ACTH released is measured by the difference in corti-costerone secretion rate before and after the injection. Amounts of vasopressin as minute as 1.0 μU to 10.0 μU release measurable quantities of ACTH. Doses of vasopressin 1,500 times this amount given intravenously have no effect on ACTH release. These findings suggest that vasopressin may be the ACTH-releasing neurohumor. It is suggested that the method may be used as an assay method for vasopressin.