Mechanical Factors Regulating Gastric Emptying of Viscous Nutrient Meals in Dogs

Abstract

SUMMARYThe 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.

Pyloric motor function during emptying of a liquid meal from the stomach in the conscious pig.

“…Induction coils, as used by Ehrlein and co-workers, signal the pyloric diameter and are not an effective method of recognizing a sequence of isolated pyloric pressure waves, as during the marked phasic pressure changes of IPPWs, the pyloric lumen rarely opens (GershonCohen, Shay & Fels, 1937;Tougas et al 1987;White et al 1983). The conclusion by Ehrlein that 'relaxation of the pyloric sphincter is more an isotonic than an isometric phenomenon' (Keinke et al 1984) is not necessarily correct. Although pyloric tone was not recorded in the pig studies, pyloric tone has been recorded with intraluminal manometric techniques in other animal preparations (Brink, Schlegel & Code, 1965;534 GASTRIC EMPTYING AND PYLORIC MOTILITY IN PIG Isenberg & Csendes, 1972;Bertiger, Reynolds, Ouyang & Cohen, 1987) and in man (Fisher & Cohen, 1973;Valenzuela, Defilippi & Csendes, 1976;Phaosawasdi & Fisher, 1982).…”

Pathophysiology of Short Bowel Syndrome

“…The pyloric sphincter, which connects the stomach and duodenum, titrates chyme based on nutrient composition and concentration. 44 This sphincter regulates the movement of liquids and smalldiameter nutrient particles into the duodenum, thereby permitting adequate mixing with bicarbonate, pancreatic, and biliary secretions. 27 Within the small intestine, the chyme is then churned locally via segmentation contractions and propagated distally via peristaltic contractions.…”

Action of Guar Gums on the Viscosity of Digestive Contents and on the Gastrointestinal Motor Function in Pigs

“…Food viscosity in particular seems to be able to change the motor function of the intestine. Previous studies showed that meal viscosity could reg ulate the gastric emptying rate in animals [ 1 ] and humans [2] by modifying the contrac tion patterns of the gastric antrum and pylo rus [3,4], More recently, Dooley et al [5] have shown that bolus viscosity significantly altered esophageal peristaltis in humans.The effects of food viscosity on small intestinal motility are less well known. Vis cous guar gum meals delayed the passage of a marker in the gastrointestinal tract of rats [6] and changed the contraction pattern of the jejunal wall in dogs [7], However, although guar gum was supposed to act by increasing the viscosity of chyme, the authors could not show a direct relationship between the meal viscosity and the intestinal motor effects.…”