ILEAL TONE IN HUMANS - EFFECTS OF LOCOREGIONAL DISTENSIONS AND EATING

Using an electronic barostat in the human terminal ileum, we studied i leal tone in response to various stimuli in 10 healthy volunteers. Pha sic activity was also measured by manometry. Graded orad (ileal) and c audad (cecal) balloon distensions did not produce any significant chan ges in ileal tone at all levels tested, even when a sensation of disco mfort was felt. A linear relationship between pressure and volume was observed during in situ isobaric ileal distensions. Meal induced a bip hasic tonic response with a brief (20 min) and immediate decrease in i ntrabag volume (64 +/- 7% of preprandial value, P < 0.05), followed by a prolonged increase in intrabag volume (158 +/- 10% ofpreprandial va lue, P < 0.05). A significant correlation was found between volume var iations and phasic activities during the first phase (r = 0.88, P < 0. 05), whereas no correlation was found during the second phase (r = 0.5 5, NS). The administration of glucagon induced a significant increase in intrabag volume from 45 +/- 5 to 70 +/- 8 ml (P < 0.05). We conclud e 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 f ollowed by a prolonged relaxation.