Sensory-motor responses to volume-controlled duodenal distension

Visceral perception and secondary peristalsis evoked by distension of the duodenum were studied in 10 healthy volunteers. An impedance planimetric probe for cross-sectional area (CSA) measurements inside a balloon and with three pressure channels was used. Balloon distensions were performed in the fed state with or without the administration of the antimuscarinic drug butylscopolamine. A modified questionnaire was used to assess the nonpainful and painful sensations. The total tension (T (total) ) and the passive tension (T (passive) ) were determined from the distensions without and with the administration of butylscopolamine, respectively. The active tension (T (active) ) was T (total) - T (passive) . The stepwise balloon distensions induced the first sensation at a volume of 33 +/- 3 mL. After administration of butylscopolamine the first sensation appeared at 42 +/- 1 mL. The perception score (PS) revealed an approximately linear increase as function of volume, CSA, pressure and tension after the first sensation. Butylscopolamine resulted in significant changes in PS score as function of volume, CSA and strain, but not as a function of pressure and tension. The frequency of the secondary peristalsis increased to the highest value (8.2 +/- 0.8 contractions min (-1) ) at a volume of 21 mL. Butylscopolamine almost abolished the distension-evoked motility. T (total) and T (passive) increased nonlinearly as a function of volume, whereas T (active) increased up to a distension volume of 33 mL and then decreased at higher volumes. Hence, the conventional length-tension diagrams as known from studies of smooth muscle strips in vitro can be reproduced in the human duodenum in vivo . This new way of studying intestinal sensation and motility may prove to have both basic and clinical importance as both passive tissue structures and the sensorimotor function are tested.