Contractile patterns and transit of fluid in canine terminal ileum

Abstract

Earlier recordings of intraluminal pressure from the terminal ileum and across the ileocolonic sphincter of dogs revealed, in addition to the usual interdigestive and digestive patterns, pressure waves that appeared to have propulsive potential. One of these, which we designated as a “prolonged propagated contraction” (PPC), was a wave of high amplitude; it had a duration much longer than the ileal slow wave and migrated rapidly through the ileum, often into the proximal colon. The other pattern was one of “discrete clustered contractions” (DCC); these were propagated bursts of rhythmic phasic waves, distinct from phase III of the interdigestive myoelectric complex. These migrated through the ileum more rapidly than did phase III. Our aims were to record the electrical and mechanical equivalents of these pressure events using only extraluminal sensors and to evaluate the capacity of these contractions to propel fluids. PPCs and DCCs were recorded by extraluminal strain gauges, and flow was assessed by recovery of a nonabsorbable marker. Phase III of the migrating motor complex propelled fluid through the ileum, but in addition DCCs and, especially, PPCs were able to empty the ileum. These latter contractions have similarities to the ileal “peristaltic rush” described by others, and we believe these waves are an important force for ileal emptying.