NUTRIENT FEEDBACK INHIBITION OF GASTRIC-EMPTYING PLAYS A LARGER ROLE THAN OSMOTICALLY DEPENDENT DUODENAL RESISTANCE

The slowing of gastric emptying by hyperosmolar solutions has been pos tulated to result from the triggering of duodenal osmoreceptor feedbac k on the stomach. We tested the idea that the inhibition of gastric em ptying by a hyperosmolar solution depended on the duodenal resistance and the triggering of nutrient-specific feedback by tracking gastric e mptying of 300 and 1,200 mosmol/kgH2O test solutions in 12 dogs in whi ch duodenal resistance was either removed (by temporarily diverting ch yme from uncorked duodenal fistula) or preserved (by keeping duodenal fistula corked). Mannitol was used to test osmolality alone, and gluco se was used to examine the combined effects of osmolality and nutrient -specific inhibitory feedback. We found that 1) the slowing effect of hyperosmolality was more marked with the duodenal resistance preserved (P < 0.05; analysis of variance), 2) the slowing effect of glucose wa s greater than that of mannitol for all conditions (P = 0.01; analysis of variance), and 3) the inhibitory effect of mannitol was localized to the duodenum. We conclude that inhibition of gastric emptying by hy perosmolar mannitol depended primarily on duodenal resistance, while t he inhibitory effect of hyperosmolar glucose depended on nutrient-spec ific feedback on the stomach more than duodenal resistance.