Effects of nutrient infusions into rat small intestinal isolated loops on gastrointestinal transit time

Abstract

Abstract Studies in the dog have shown that when equicaloric nutrients are infused into the distal small intestine, glucose is the most potent inhibitor of proximal small intestinal motility. Studies in man and rat have shown lipid to be the most potent inhibitor of gastrointestinal motility, but the nutrients were not infused at equicaloric loads. These studies aimed to investigate the effect of infusing nutrients (Intralipid 20%, protein 8g/100 ml, glucose 50 mM, rice starch 5 g/ 100 ml), either alone or in combination, into isolated jejunal or ileal loops on stomach to caecum transit time (SCTT) to establish whether regional control of gastrointestinal motility by specific nutrients exists. The effects of infusing equicaloric nutrients (0.2 and 2 kcal) into the ileal loops on SCTT were also investigated. SCTT was significantly delayed when Intralipid (P < 0.001) was infused into ileal loops and when glucose was infused into jejunal loops (P < 0.01). Infusing protein with lipid abolished the effect of ileal lipid on SCTT, but infusing glucose with lipid still produced a significant delay in SCTT of the meal. Infusing either lipid or protein at 2 kcal delayed SCTT, but equicaloric loads of glucose had no effect. These results suggest both species and regional differences in the control of gastrointestinal motility.