EFFECTS OF NUTRIENT INFUSIONS INTO RAT SMALL-INTESTINAL ISOLATED LOOPS ON GASTROINTESTINAL TRANSIT-TIME

Studies in the dog have shown that when equicaloric nutrients are infu sed into the distal small intestine, glucose is the most potent inhibi tor of proximal small intestinal motility. Studies in man and rat have shown lipid to be the most potent inhibitor of gastrointestinal motil ity, but the nutrients were not infused at equicaloric loads. These st udies aimed to investigate the effect of infusing nutrients (Intralipi d 20%, protein 8 g/100 ml, glucose 50 mM, rice starch 5 g/100 ml), eit her alone or in combination, into isolated jejunal or ileal loops on s tomach to caecum transit time (SCTT) to establish whether regional con trol of gastrointestinal motility by specific nutrients exists. The ef fects of infusing equicaloric nutrients (0.2 and 2 kcal) into the ilea l loops on SCTT were also investigated. SCTT was significantly delayed when Intralipid (P < 0.001) was infused into ileal loops and when glu cose was infused into jejunal loops (P < 0.01). Infusing protein with lipid abolished the effect of ileal lipid on SCTT, but infusing glucos e with lipid still produced a significant delay in SCTT of the meal. I nfusing either lipid or protein at 2 kcal delayed SCTT, but equicalori c loads of glucose had no effect. These results suggest both species a nd regional differences in the control of gastrointestinal motility.