Gastrin

Abstract

The existence of the pyloric chemical phase of gastric secretion has been sufficiently proved experimentally, but its hormonal mechanism, postulated by Edkins, has been doubted. The many attempts made to establish the chemical identity of the hypothetical “gastrin” did not produce conclusive results (for literature, see Babkin and Ivy). Recently Sacks, Ivy, Burgess and Vandolah isolated histamine from the pyloric mucosa, and concluded that “histamine is the gastric hormone, or if not, there is no gastric hormone, or the gastric hormone has never been extracted from pyloric mucosa.” This view was reiterated recently by Schnedorf and Ivy. The experiments reported below demonstrate clearly that a protein-like substance, having a specific secretagogue effect on the fundic glands can be extracted in a histamine-free form from the pyloric mucosa, and in lesser quantity from the duodenum. Twenty-one experiments were carried out on cats under chloralose-urethane anesthesia, in which the gastric and pancreatic secretion, the bile flow, and occasionally also the blood pressure, following intravenous administration of various extracts prepared from different parts of the dog's stomach and intestines, were studied. The chemical procedure that was adopted for the preparation of crude extracts is as follows: The mucous membrane from different parts of the stomach of freshly killed, fasting dogs is removed with the aid of a knife and minced; intestinal mucosa is removed by scraping and ground with sand. The tissues are boiled with 10 volumes of n/10 HCl, partially neutralized with n/l NaOH to the point where it remains only slightly acid to Congo. After cooling, the extract is centrifuged. The supernatant fluid is filtered through cotton and precipitated with 10% crystalline trichloroacetic acid. The precipitate is centrifuged and washed 3 times with 40 to 50 volumes of 10% solution of trichloroacetic acid in saline, twice with 50 volumes of acetone, once with benzene, and twice with ether, and dried in vacuo.