Ileal tone in humans: effects of locoregional distensions and eating

Using an electronic barostat in the human terminal ileum, we studied ileal tone in response to various stimuli in 10 healthy volunteers. Phasic activity was also measured by manometry. Graded orad (ileal) and caudad (cecal) balloon distensions did not produce any significant changes in ileal tone at all levels tested, even when a sensation of discomfort was felt. A linear relationship between pressure and volume was observed during in situ isobaric ileal distensions. Meal induced a biphasic tonic response with a brief (20 min) and immediate decrease in intrabag volume (64 +/- 7% of preprandial value, P < 0.05), followed by a prolonged increase in intrabag volume (158 +/- 10% of preprandial value, P < 0.05). A significant correlation was found between volume variations and phasic activities during the first phase (r = 0.88, P < 0.05), whereas no correlation was found during the second phase (r = 0.55, NS). The administration of glucagon induced a significant increase in intrabag volume from 45 +/- 5 to 70 +/- 8 ml (P < 0.05). We conclude that 1) regional distensions do not influence ileal tone and phasic motility, 2) the ileum does not show accommodation to distensions, and 3) meal produces an immediate increase in phasic and tonic activity followed by a prolonged relaxation.