A Histamine-Like Component of Commercial Pitressin.

Abstract

Commercial Pitressin contains minute amounts of a histamine-like component apparently bound to the polypeptide but which can be concentrated and rendered capable of inducing physiological responses characteristic of histamine when Pitressin is subjected to strong acid hydrolysis and the pressor activity destroyed. Extracts of commercial oxytocin contained but 1/10 the vasodepressor activity of Pitressin extracts. Highly concentrated acid extracts of Pitressin are extremely active in releasing ACTH from pituitaries incubated with such extract in the Warburg apparatus. The incubation fluid given in small amounts by vein to hypo-physectomized rats induces a highly significant fall in adrenal ascorbic acid. Control pituitaries obtained in the same manner and similarly incubated but without the extract gave only negative results in hypophysectomized animals.