DIFFERENCES EXIST IN PASSIVE ELASTIC WALL PROPERTIES BETWEEN SEGMENTSOF ISOLATED GUINEA-PIG DISTAL ILEUM AND DUODENUM IN-VITRO

The aim was to study and to compare passive biomechanical wall propert ies in the isolated duodenum and distal ileum of the guinea-pig. Stepw ise inflation of an intraluminal balloon, in which the pressure and cr oss-sectional area were measured simultaneously, provided the distensi on stimulus. Biomechanical wall parameters such as wall tension and co mpliance were calculated from steady state values of these measurement s. Smooth muscle relaxation was obtained by adding 10(-3) M papaverine to the organ bath. Cross-sectional area always reached equilibrium wi thin the two-minute inflation period. The pressure-cross-sectional are a relations showed a higher degree of hysteresis in the ileum than in the duodenum (P < 0.01). Cross-sectional area and wall tension in dist al ileum was higher than those in duodenum (P < 0.001). Compliance was at pressures up to 3 kPa significantly higher in the ileum. At the hi ghest induced pressures, compliance was the same for the two segments. The model provides the opportunity for studying passive biomechanical wall properties in the isolated small intestine. Biomechanical differ ences were found between the proximal and distal small intestine. Thes e properties may be related to the specialized functions of the two se gments, e.g. flow properties.