AJP - Gastrointestinal and Liver Physiology, Vol 265, Issue 3 540-G546, Copyright © 1993 by American Physiological Society

ARTICLES

Duodenal acid-induced inhibition of gastric motility and emptying in rats

H. E. Raybould and H. H. Holzer
Center for Ulcer Research and Education, Veterans Affairs Medical Center West Los Angeles, California 90073.

The mechanism by which acid in the duodenum inhibits proximal gastric motor function and delays emptying was investigated in urethan-anesthetized and awake rats. Gastric motility inhibited by duodenal acid (0.2 N HCl) in urethan-anesthetized rats was attenuated by 68 and 54%, respectively, by functional ablation of the vagal or spinal sensory innervation with capsaicin. 5-Hydroxytryptamine3 receptor blockade with zacopride (0.2 mg/kg ip) or cholecystokinin (CCK)-A-type receptor blockade with MK-329 (1 mg/kg ip) had no effect on the motility response to acid. In awake rats with chronically implanted gastric and duodenal cannulas, perfusion of the duodenum with acid (0.1 and 0.2 N HCl) inhibited gastric emptying of a nonnutrient liquid (38 and 59%, respectively). Blockade of CCK-A-type receptors reduced by 30% inhibition of gastric emptying induced by 0.1 N HCl. However, functional ablation of the vagal or spinal sensory innervation, 5-hydroxytryptamine3 receptor blockade, or immunoneutralization of secretin by systemic administration of a polyclonal antibody (no. 7842, 1 ml ip) had no effect on acid-induced (0.1 N HCl) inhibition of gastric emptying. Perfusion of the duodenum with 0.2 N HCl but not 0.1 N HCl inhibited proximal gastric motility in awake rats. These results suggest that 1) a duodenal acid load inhibits gastric emptying in part by a mechanism involving CCK and 2) decreased proximal gastric motility plays a minor role in inhibition of gastric emptying in response to acid.

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