Mechanical factors regulating gastric emptying of viscous nutrient meals in dogs

The aim of this study was to determine the mechanisms controlling gastric emptying of viscous meals. In four conscious dogs the antral, pyloric and duodenal activities were recorded with strain-gauge transducers and induction coils during gastric evacuation of an inert cellulose meal and of four nutrient meals containing mannitol, casein, glucose or oleic acid. Gastric emptying and the internal pyloric and duodenal diameters were measured from radiographs. The nutrients delayed gastric emptying and diminished to a various extent the antral and duodenal motility as well as the pyloric opening. The motility gradient between antral and duodenal activity showed no relationship to the emptying delay. The duodenal lumen was reduced and the propulsive contractions of the duodenum decreased while the segmental activity increased. The findings suggest that gastric emptying is controlled by (1) the depth of the antral waves, (2) the pyloric opening, (3) the receptive relaxation of the duodenum and (4) the type of the duodenal contractions. By contrast the sequence of the terminal antral contraction and the pyloric closure, as well as the co-ordination between pyloric and duodenal contractions, played no important role in regulating gastric emptying.