Colonic migrating and nonmigrating motor complexes in dogs

We report here the characteristics of a cyclic motor activity in the colon of conscious dogs and its relationship to small intestinal migrating motor complexes (MMCs). The colonic motor activity was recorded by four equispaced strain gauges and small intestinal myoelectric activity by four equispaced bipolar electrodes. The colonic motor activity was characterized by rhythmic bursts of contractions. The mean durations of bursts of contractions varied from 7.0 to 11.5 min at the four colonic recording sites. Those bursts of contractions which migrated over at least three recording sites were called colonic migrating motor complexes (CMMCs). All other patterns of bursts of contractions were called colonic nonmigrating motor complexes (CNMCs). A total of 160 CMMCs were recorded during a total recording period of 132 h; 151 CMMCs migrated caudad and 9 orad. The mean period of caudad migrating CMMCs was 53.3 ± 5.4 (SE) min, and their mean migration time was 11.3 ± 1.2 (SE) min. The onset of CMMCs was not temporally related to the onset of small intestinal migrating myoelectric complexes in the duodenum or their arrival in the terminal ileum. CMMCs did not have phases I to IV like those of small intestinal MMCs, but two consecutive CMMCs were separated by a quiescent state or by one or more randomly occurring bursts of contractions (CNMCs).