To study the effects of intraileal nutrients on human pancreatic secretion and gastrointestinal motility, nine healthy subjects were intubated with an oroileal multilumen tube for ileal perfusion, duodenal juice aspiration, and intestinal motility recording. The duodenum was perfused continuously with essential amino acids to induce submaximal stimulation of pancreatic enzyme secretion and fed motility pattern. Additional ileal perfusion with carbohydrate at quantities similar to those observed under physiological late postprandial conditions or fat at isocaloric loads significantly decreased pancreatic enzyme outputs by greater than 80% (P less than 0.001) compared with saline. Ileal carbohydrate or fat induced a duodenal motor activity front that migrated distally and was followed by reduced motility. In summary, ileal delivery of small quantities of nutrient markedly decreased endogenously stimulated pancreatic enzyme secretion in humans. This was associated with specific changes in fed intestinal motility that converted to patterns characteristic of the interdigestive state. Our findings suggest that the distal small intestine may participate in the late postprandial regulation of gastrointestinal function in humans.

Following ingestion of a meal, unabsorbed nutrients may reach the distal intestine partly after the termination of the prandial period, i.e., in the presence of interdigestive motor and secretory patterns. To determine if interdigestive motility and pancreatic enzyme secretion are modulated by the delivery of nutrient into the ileal lumen, six fasting volunteers were intubated with an oroileal multilumen tube system that permitted multiple small intestinal manometry, gastric and duodenal aspiration, and perfusions of marker and test solutions. Ileal perfusions of nutrient or saline solutions were started during phase I of the interdigestive motility cycle. Ileal perfusion with carbohydrate or lipids increased the duration of motor quiescence and decreased the length of the interdigestive cycle, mainly by decreasing the proportion of phase I1 activity compared with ileal saline (p < 0.01).Pancreatic outputs of amylase, trypsin, and chymotrypsin prior to ileal perfusions were low because, due to the protocol, perfusions were started during phase I. With ileal saline, enzyme outputs increased (p < 0.05) in association with the occurrence of phase I1 motility, as expected. By contrast, ileal carbohydrate and triglyceride perfusion prevented the phase 11-associated increase in enzyme outputs (p < 0.05). The data suggest that the presence of nutrients within the ileal lumen may modulate interdigestive motor and pancreatic functions.