REGULATION OF GASTRODUODENAL EMPTYING OF SOLIDS BY GASTROPYLORODUODENAL CONTRACTIONS

We investigated the mechanisms of regulation of gastroduodenal emptying of solid meals by gastropyloroduodenal contractions in six conscious dogs. The spatial and temporal parameters of gastropyloroduodenal contractions were correlated with the rate of gastroduodenal emptying. The rate of gastroduodenal emptying exhibited a significant positive correlation with the 1) mean frequency of corporeal and antral contractions; 2) mean frequency, amplitude, duration, and area under pyloric contractions; 3) percentage of contractions that propagated in the distal duodenum, and the mean distance of their propagation; 4) percentage of contractions that propagated within the stomach, including the pylorus; 5) percentage of contractions that propagated from the antrum or the pylorus to the proximal duodenum; and 6) ratio of the mean frequency of contractions in the antrum to that in the proximal or the distal duodenum during the entire period of gastroduodenal emptying. The major factors that exhibited a significant negative correlation with gastroduodenal emptying were the total number, amplitude, duration, and area under contractions in the whole duodenum during the entire period of gastroduodenal emptying. We conclude that the antropyloroduodenal contractions, acting as a peristaltic pump, are a major factor in the regulation of gastric emptying of solid meals. The propagating contractions in the distal duodenum promote gastric emptying by rapidly removing the chyme from this area, whereas the nonpropagated contractions in the duodenum may provide a mechanical resistance to gastric emptying.