SECRETIN — one of peptide gastrointestinal hormones. It is opened by Baileys (W. M of Bayliss) and E. Starling in 1902. The term «hormone» was for the first time applied in relation to
S. S. is synthesized generally in S-cells of a mucous membrane duodenum (see) and, to a lesser extent, in a proximal part of a jejunum (see. Intestines ). In pure form hormone was emitted in 1962 Mr. Mutt and Yorpes (V. Mutt, J. E. Jorpes), and in 1966 Bodansky (M. Bodanszky) with sotr. synthesized it.
The molecule C. consists of 27 amino-acid remains located in the sequence: Гис-Сер-Асп-Гли-Тре-Фен-Тре-Сер-Глу-Лей-Сер-Арг-Лей-Арг-Асп-Сер-Ала Арг-Лей-Гли-Арг-Лей-Лей-Гли-Глу-Лей-Вал-NH 2 . Pier. the weight (weight) of S. is equal to 3035.
Beyliss and E. Starling assumed that S. is formed of the predecessor deposited in a cell — prosecretin. More detailed studying of ways of synthesis of S. allowed to make the conclusion that secretin in S-cells remains as the strong basis in electrostatic connected state with the ionized carboxyl groups of cellular proteins; at receipt in a duodenum salt to - you as a part of the contents evacuated from a stomach this charge decreases, S. is released and transported from cells in a blood stream. Release of hormone begins in a duodenum at pH apprx. 4,5 and is in direct dependence on the acidified area of a gut of hydrogen ion concentration. At the person increase in maintenance of S. in a blood plasma is noted at pH within 2 — 3 in the intraduodenal environment. S.'s release at nervous influences and action of other chemical agents is not proved.
The page sharply increases the volume of secretion and release of bicarbonates a pancreas, stimulating tsentroatsinozny and other cells of its exocrine part. This main effect of effect of secretin amplifies other neurohumoral factors, taking action after meal. Besides, S. causes strengthening of secretion of electrolytes a liver (increases secretion and reduces a reabsorption of sodium and bicarbonates) and a duodenum; strengthens a cholepoiesis (see. Bile production ); cholecystokinin-pancreozymin exponentiates a promoting effect (see. Cholecystokinin ) on motility bilious, a bubble and fermentovydelitelny activity of a pancreas, exerting on it trophic impact; slows down secretion salt to - you with simultaneous strengthening of a pepsinia glands of a stomach (see. Pepsin ); raises an inkretion insulin (see), brakes an inkretion glucagon (see) and gastrin (see); reduces peristaltic activity stomach (see), duodenum and tone of the lower esophageal sphincter, and also speed of proliferation of intestinal epithelial cells; raises a blood stream in a pancreas, invertazny and maltose activity of a small bowel; increases cordial emission of blood and a blood stream in abdominal organs; strengthens renal release of water, sodium, potassium and bicarbonates; stimulates liioliz (see. Digestion ).
The half-cycle of existence of S. in a blood-groove makes 2,5 — 3 min. Precisely the place where there is a destruction of hormone, is not established, but to number of bodies, in to-rykh this process is carried out, carry kidneys and a liver. Besides, S.'s hydrolysis is carried out by fermental systems of blood and an endothelium of blood vessels; a small amount of hormone is removed from a blood-groove with urine and bile.
S.'s effects are implemented in the course of its interaction with membrane receptors of target cells by stimulation of adenylatecyclase and change of content of cyclic adenosinemonophosphate.
S.'s release is oppressed at reduction of an intraduodenal atsidifikation (secretory insufficiency of a stomach), Zollinger's syndrome — Ellisona (see. Zollingera — Ellisona a syndrome ), resection of a duodenum, duodenitis, peptic ulcer of a duodenum.
The page in blood serum is defined by a radio immunological method (see). Its contents in a blood plasma is normal can reach 150 pg/ml.
The purified biological and synthetic drugs C. are used with the diagnostic purpose for stimulation of pancreatic secretion at a research of a pancreas. With to lay down. the purpose drugs C. use as inhibitor of secretion salt to - you glands of a stomach at a peptic ulcer of a duodenum.
Bibliography: Gastrointestinal hormones and pathology of the alimentary system, under the editorship of M. Grossman, etc., the lane with English, page 138, etc., M., 1981; At about l e in A. M. Enterinovaya (intestinal hormonal) system, JI., 1978, bibliogr.; Physiology of endocrine system, under the editorship of V. G. Baranov, page 414, JI., 1979, bibliogr.; In 1 about-o'm S. R. and. R about 1 a k J. M of The new peptide hormones of the gut and their clinical significance, Acta gastroenterol. belg., v. 41, p. 371, 1978; Dock-r an at G. J. Molecular evolution of gut hormones, application of comparative studies on the regulation of digestion, Gastroenterology, v. 72, p. 344, 1977, bibliogr.; Gardner J. D. Receptors for gastrointestinal hormones, ibid., v. 76, p. 202, 1979, bibliogr.; Heitz P. U. The neuroendocrine system of the gastrointestinal tract, Path. Res. Pract., v. 165, p. 333, 1979, bibliogr.