Appearance of peristaltic reflex in isolated guinea pig ileum in response to boluses of air, water, oil, and cellulose.

Distension of an isolated preparation of guinea pig ileum triggers the peristaltic reflex, a characteristic movement of the intestinal walls which generates luminal pressures and clearance of luminal contents. To determine how the reflex responds to properties of luminal contents, we compared the responses triggered by boluses of air, oil, and cellulose to boluses of Krebs' solution. We found that oil and cellulose increased pressures and contraction length and decreased outflow. Cellulose, but not oil, slowed the velocity with which the contraction propagated and increased the delay with which the end point (upstream edge) of the contraction started to propagate after the lead point (downstream edge). Air tended to produce short contraction segments and high velocity. We conclude that bolus properties such as viscosity determine the response that isolated intestinal segments generate to distension. Response patterns are reflected in contraction length, propagation velocity, and other visual parameters that define wall movements.