Effect of casein and casein hydrolysate on small bowel motility and D-xylose absorption in dogs.

Food administration is followed by the appearance of a small intestinal pattern of irregular contractions. Studies on the relationship between intestinal motor activity, transit and absorption have yielded contradictory results. Since previous studies have shown that casein and casein hydrolysate led to a decrease of small intestinal motor activity and transit, the aim was to evaluate the effect of these nutrients on small intestinal motility and D-Xylose absorption. Studies were performed in five dogs with a duodenal fistula; motility was recorded by means of six infused catheters and external transducers. Three test solutions with the same osmolality, lactulose, casein and casein hydrolysate, were continuously infused through the duodenal cannula. D-Xylose was injected in the duodenum and plasma levels determined at regular intervals. Absorption of D-Xylose was greatest during the administration of casein hydrolysate, the lowest levels were seen with lactulose and intermediate levels were obtained with casein. The effect of casein hydrolysate on small intestinal motility was characterized by a decrease in the frequency of contractions. Propulsive contractions were decreased after the infusion of both casein and casein hydrolysate. Lactulose infusion was followed by the greatest motor activity of both frequency and propulsive contractions. These results suggest that the motor patterns observed with casein and casein hydrolysate lead to increased intestinal absorption of D-Xylose.