Small-intestine absorption during continuous intraduodenal infusion of nutrients in dogs

Motility and exocrine and endocrine secretions of the gastrointestinal trac t are modified during postprandial periods. Experimental evidence suggests that nutrients stimulate small-intestine absorption, but the mechanisms inv olved are uncertain. Further, the effects of mixing nutrients with differen t physicochemical compositions on absorption and motility are not completel y elucidated. With the use of a canine model, we investigated the effects o f a mixture of differents lipids and proteins on small-intestine motility a nd absorption. Two cannulae, one in the proximal duodenum and one in the di stal ileum, were implanted in the dogs. Absorption of a continous duodenal infusion of eight test mixtures consisting of long- and medium-chain fatty- acid triacylglycerols, soy protein and its hydrolysate, casein and its hydr olysate, and variable amounts of glucose, and glucose polymer were analyzed by measuring the volume, concentration, and total amount of triacylglycero ls, nitrogen, and glucose recovered from the ileal cannula. Significant dif ferences in absorption were observed across test mixtures. Significantly lo wer absorption of H2O and nutrients was observed with test mixtures prepare d with medium-chain fatty-acid triacylglycerols and soy protein compared wi th test mixtures prepared with corn oil, casein, and hydrolysates of both p roteins. We concluded that the physicochemical characteristics of nutrients in elemental diets continuously infused into the duodenum are important fo r determining small-intestine absorption. Nutrition 2001:17: 254-258. (C) E lsevier Science Inc. 2001.