AJP - Gastrointestinal and Liver Physiology, Vol 252, Issue 1 136-G142, Copyright © 1987 by American Physiological Society
Coordination of electrical activities in muscle layers of the pig colon
J. D. Huizinga, E. Chow, N. E. Diamant and T. Y. el-Sharkaway
Simultaneous recording of electrical activities from the circular and
longitudinal muscle layers of the pig colon was performed in vitro to study
possible coordination of activities. The electrical activity of both muscle
layers consisted of electrical oscillations with superimposed spikes. The
frequency range of the electrical oscillations in the circular muscle was
0.5-3.5 cycles per minute (cpm) and in the longitudinal muscle 24-42 cpm.
Coordination of the activities of both muscle layers occurred consistently
only after stretch or cholinergic stimulation. Then it occurred in a unique
fashion. Each oscillation in the circular muscle layer occurred at the same
time as the onset of a burst of oscillations in the longitudinal muscle. In
addition, multiple simultaneous recordings of the electrical activities
from each muscle layer were obtained showing that within the circular
muscle layer electrical oscillations were phase locked in the
circumferential direction and along the long axis of the colon. They
appeared to propagate in either the oral or aboral direction. In
tetrodotoxin (with stretch as stimulus) and also in presence of carbachol,
bursts of oscillations in the longitudinal muscle layer were phase locked
circumferentially (in the different taeniae) and longitudinally. This study
shows that the muscle layers in the colon, which have different myogenic
electrical activities, can obtain a high level of coordination.
