Myoelectric correlates of colonic motor complexes and contractile activity.

This report describes the myoelectric correlates of colonic motor complexes and contractile activity. A set of four bipolar electrode/strain-gauge pairs was surgically implanted on the colon of each of the five dogs used in this study. Each recording site showed a cyclic occurrence of bursts of contractions called contractile states. The colonic muscle contracted mainly at two frequencies during a contractile state, long-duration contractions at 0.5-2 cycles/min and short-duration contractions at 4-6 cycles/min. The long-duration contractions at 0.5-2 cycles/min were associated with bursts of contractile electrical complex (electrical oscillations at 25-40 cycles/min) and continuous electrical response activity on a 1:1:1 basis. The short-duration contractions at 4-6 cycles/min were associated with bursts of discrete electrical response activity on a 1:1 basis. Those episodes of contractile electrical complex, continuous electrical response activity, and discrete electrical response activity that migrated orad or aborad over at least half the length of the colon were called colonic migrating myoelectric complexes. All other patterns of occurrence of these episodes were called colonic non-migrating myoelectric complexes. A total of 184 colonic migrating myoelectric complexes were recorded during a total recording period of 148 h: 173 migrated caudad and 11 orad. The mean period of colonic migrating myoelectric complexes was 52.7 +/- 6.5 (SE) min. We conclude that the characteristics of colonic migrating myoelectric complexes are strikingly different from those of migrating myoelectric complexes in the small intestine.