Differences exist in passive elastic wall properties between segments of isolated guinea‐pig distal ileum and duodenum in vitro

Abstract

Abstract The aim was to study and to compare passive biomechanical wall properties in the isolated duodenum and distal ileum of the guinea‐pig. Stepwise inflation of an intraluminal balloon, in which the pressure and cross‐sectional area were measured simultaneously, provided the distension stimulus. Biomechanical wall parameters such as wall tension and compliance were calculated from steady state values of these measurements. Smooth muscle relaxation was obtained by adding 10‐3 m papaverine to the organ bath. Cross‐sectional area always reached equilibrium within the two‐minute inflation period. The pressure‐cross‐sectional area relations showed a higher degree of hysteresis in the ileum than in the duodenum (P < 0.01). Cross‐sectional area and wall tension in distal ileum was higher than those in duodenum (P < 0.001). Compliance was at pressures up to 3 kFa significantly higher in the ileum. At the highest 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 differences were found between the proximal and distal small intestine. These properties may be related to the specialized functions of the two segments, e.g. flow properties.