Duodenal acid-induced inhibition of gastric motility and emptying in rats.
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.
Raybould
H E
HE
Center for Ulcer Research and Education, Veterans Affairs Medical Center West Los Angeles, California 90073.
Hölzer
H H
HH
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004386:Duodenum / Q000502:physiology*; D005746:Gastric Emptying / Q000187:drug effects*; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006851:Hydrochloric Acid / Q000494:pharmacology*; D008297:Male; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors; D013562:Sympathectomy; D014628:Vagotomy
D011949:Receptors, Cholecystokinin; D006851:Hydrochloric Acid; D002211:Capsaicin