Gastric secretion gastrin

The gastric phase is elicited by the presence of food in the stomach. Distension of the stomach wall, as well as the presence of protein, caffeine, and alcohol, enhances gastric secretion. This phase is mediated by the intrinsic nerves, the vagus nerve, and gastrin. Each of these mechanisms promotes secretion of HC1 and pepsinogen. 

Acid rebound Antacids may cause dose-related rebound hyperacidity because they may increase gastric secretion or serum gastrin levels. 

Bombesin 54 120,121), isolated from frog skin, is thought to have antidiuretic and antihypertensive properties. It stimulates the secretion of gastrin, pancreatic and gastric secretion, and causes contraction of the gallbladder. 

Yuki H, Nishida A, Miyake A et al. (1997) YM022, a potent and selec-tive gastrin/CCK-B receptor antagonist, inhibits peptone meal-induced gastric secretion in Heidenhain pouch dogs. Dig Dis Sci 42 707-714... 

Gastric secretion and motility are controlled by both nervous and hormonal mechanisms. The vagus initiates the cephalic phase of secretion in response to the sight or smell of food, before food is eaten. The gastric phase occurs when food enters the stomach and is controlled both by intrinsic nerve reflexes in the stomach wall and released gastrin. The third, or intestinal, phase of secretion is coordinated by nervous and hormonal mechanisms to limit the release of the chyme from the stomach into the duodenum and reduces further acid secretion. 

The presence of food in the stomach evokes gastric secretion. The principal stimuli include distension of the stomach and the presence of amino acids and peptides. Distension of the stomach stimulates mechanor-eceptors that bring about secretion of acetylcholine, hydrochloric acid, and gastrin. 

Levant JA, Walsh JH, Isenberg JI. Stimulation of gastric secretion and gastrin release by single oral doses of calcium carbonate in man. N Engl J Med 1973 289(ll) 555-8. 

Gastric acid secretion can be inhibited by several mechanisms including acid in the stomach (pH 3 inhibits gastrin release), acid in the duodenum, the presence of fat in the pancreas, and hypertonic fluids or hyperglycemia. Somatostatin, a hormone produced by antral mucosal endocrine cells (D cells), inhibits the release of gastrin by directly inhibiting the parietal cells. Somatostatin is also present in other GI tissue and the pancreas. C cells, endocrine cells in the proximal small intestine, secrete secretin in response to mucosal acidification, which also decreases gastric secretion. 

Gastric Phase. Gastrin is the main mediator of acid secretion. Acid secretion occurs h response to both the presence of nutrients and the physical distension produced by food entering the stomach. Distension-induced gas.-trie acid secretion, relative to the total amount of acid released, is species dependent (human = 20% dog = 50% rat = 38%). The chemical constituents of a meal are the strongest stimulant of gastrin release and acid output during... 

Effects on the Gastrointestinal Tract. Somatostatin inhibits both the gastric secretion induced by gastrin and the release of gastrin,20 which suggests a potential utility for the treatment of ulcers. 

MEN type I is characterized by hyperparathyroidism, together with pituitary and pancreatic tumours. Hyper-calcaemia caused by excess PTH. secretion is the dominant feature in this syn-drt)me. The most common pituitary tumour is a non-functioning chromophobe adenoma which, although it dws not secrete a hormone itself, may have effects on the secretion of other anterior pituitary hormones. The most common pancreatic tumour in MEN type 1 is an islet cell tumour secreting gastrin. The secretion of gastrin may lead to gastric ulceration. 

Gastrinomas secrete gastrin which causes gastric acid hypersecretion and ulceration. 

Histamine, as a normal constituent of the gastric mucosa, controls both microcirculation and gastric secretion. The gastric secretagogs are acetylcholine, histamine, and gastrin. The action of acetylchoUne is blocked by atropine, and the action of histamine is blocked by cimetidine, burimamide, and metiamide. No specific antagonist is available for gastrin. 

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