Electrophysiologic control of motility in the human colon

Characteristics of electrical activities, and the relationship between electrical and motor activities, were studied in circular and longitudinal (taenia) muscle of the human colon that was obtained from 21 individuals. Recordings were obtained with suction electrodes, the sucrose-gap method, and microelectrodes. The circular muscle electrical activity consisted of oscillatory activity of relatively low amplitude, with a frequency range from 4.5 to 60 cycle/min. Spiking activity was present on most oscillations. Contractile activity was associated with individual oscillations at frequencies below 12 cycle/min. Contractions related to periods of oscillations at frequencies above 12 cycle/min showed summation resulting in prolonged contractions. In these periods, oscillations were either of relatively high amplitude, or had superimposed spiking activity. Longitudinal muscle activity consisted of slow electrical oscillations at frequencies between 24 and 36 cycle/min with spiking activity superimposed on most oscillations. Contractions were related to bursts of such activity. These findings provide the electrophysiologic basis for short and prolonged phasic contractions and for sustained contractions of the human colon muscle layers. Activities in both muscle layers were myogenic in nature, were very sensitive to stretch, and could be initiated or modulated by nervous activity.