Acid inhibition by intestinal nutrients mediated by CCK-A receptors but not plasma CCK.
We examined the role of CCK-A receptors in acid inhibition by intestinal nutrients. Gastric acid and plasma CCK and gastrin levels were measured in rats with gastric and duodenal fistulas during intragastric 8% peptone and duodenal perfusion with saline, complete liquid diet (CLD; 20% carbohydrate, 6% fat, and 5% protein), and the individual components of CLD. Acid output was significantly inhibited (50-60%) by CLD, lipid, and dextrose. Plasma CCK was significantly increased by CLD (from 2.6 +/- 0.3 to 4.8 +/- 0.5 pM) and lipid (4.6 +/- 0.5 pM). CCK levels 50-fold higher (218 +/- 33 pM) were required to achieve similar acid inhibition by exogenous CCK-8 (10 nmol x kg(-1) x h(-1) iv). Intestinal soybean trypsin inhibitor elevated CCK (10.9 +/- 2.5 pM) without inhibiting acid secretion. The CCK-A antagonist MK-329 (1 mg/kg iv) reversed acid inhibition caused by CLD, lipid, and dextrose. Peptone-stimulated gastrin (21.7 +/- 1.9 pM) was significantly inhibited by CLD (14.5 +/- 3.6 pM), lipid (12.3 +/- 2.2 pM), and dextrose (11.9 +/- 1.5 pM). Lipid and carbohydrate inhibit acid secretion by activating CCK-A receptors but not by altering plasma CCK concentrations.
Lloyd
K C
KC
Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis 95616, USA. kclloyd@ucdavis.edu
Wang
J
J
Solomon
T E
TE
D000818:Animals; D002766:Cholecystokinin / Q000097:blood*; D020109:Devazepide / Q000494:pharmacology; D004032:Diet; D004386:Duodenum / Q000378:metabolism; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism; D005755:Gastrins / Q000097:blood; D006727:Hormone Antagonists / Q000494:pharmacology; D008297:Male; D009747:Nutritional Physiological Phenomena; D010461:Peptones / Q000494:pharmacology; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin / Q000378:metabolism*
D005755:Gastrins; D006727:Hormone Antagonists; D010461:Peptones; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin; D002766:Cholecystokinin; D020109:Devazepide