AJP - Gastrointestinal and Liver Physiology, Vol 260, Issue 4 636-G645, Copyright © 1991 by American Physiological Society

ARTICLES

Slow-wave activity in colon: role of network of submucosal interstitial cells of Cajal

R. Serio, C. Barajas-Lopez, E. E. Daniel, I. Berezin and J. D. Huizinga
Intestinal Diseases Research Unit, McMaster University, Hamilton, Ontario, Canada.

The present study compares the electrophysiological properties of two preparations dissected from the canine colon circular muscle layer: first, containing the submucosal network of interstitial cells of Cajal (ICC) with two to four associated smooth muscle cell layers, and second, a circular muscle preparation devoid of the submucosal ICC network. In the ICC-rich preparations, consistent slow-wave activity was observed with prolonged plateau potentials of approximately 10-s duration. The plateau potentials were sensitive to D 600. In approximately 45% of circular muscle preparations devoid of the submucosal ICC network (confirmed using electron microscopy) slow waves, of different waveshape, were recorded at frequencies identical to those in whole circular muscle preparations. These slow waves did not show a plateau potential. Compared with ICC-rich preparations with a resting membrane potential of about -80 mV, circular muscle preparations had lower membrane potentials, about -70 mV when active, and about -60 mV when quiescent. Heptanol (1 mM) electrically uncoupled cells, since it abolished electrotonic current spread and allowed measurement of the input resistance by intracellular current injection. Heptanol also affected ionic conductances. Heptanol abolished slow waves; the underlying mechanism needs further investigation. In the presence of heptanol, cells in the isolated ICC network and in circular smooth muscle preparations showed spontaneous hyperpolarizing potential fluctuations at a frequency of four to six per second. These oscillations were abolished by current-induced hyperpolarization and TEA (30 mM) and are therefore likely due to spontaneously active K+ conductance.

This article has been cited by other articles:

				S. K. Sarna Are interstitial cells of Cajal plurifunction cells in the gut? Am J Physiol Gastrointest Liver Physiol, February 1, 2008; 294(2): G372 - G390. [Abstract] [Full Text] [PDF]

				G. J. Christ, M. Spektor, P. R. Brink, and L. Barr Further evidence for the selective disruption of intercellular communication by heptanol Am J Physiol Heart Circ Physiol, June 1, 1999; 276(6): H1911 - H1917. [Abstract] [Full Text] [PDF]

				M. Jimenez, J. R. Borderies, P. Vergara, Y.-F. Wang, and E. E. Daniel Slow waves in circular muscle of porcine ileum: structural and electrophysiological studies Am J Physiol Gastrointest Liver Physiol, February 1, 1999; 276(2): G393 - G406. [Abstract] [Full Text] [PDF]

				R. Hagger, S. Gharaie, C. Finlayson, and D. Kumar Regional and transmural density of interstitial cells of Cajal in human colon and rectum Am J Physiol Gastrointest Liver Physiol, December 1, 1998; 275(6): G1309 - G1316. [Abstract] [Full Text] [PDF]

				E. E. Daniel, Y.-F. Wang, and F. S. Cayabyab Role of gap junctions in structural arrangements of interstitial cells of Cajal and canine ileal smooth muscle Am J Physiol Gastrointest Liver Physiol, June 1, 1998; 274(6): G1125 - G1141. [Abstract] [Full Text] [PDF]

				G. Lu, X. Qian, I. Berezin, G. L. Telford, J. D. Huizinga, and S. K. Sarna Inflammation modulates in vitro colonic myoelectric and contractile activity and interstitial cells of Cajal Am J Physiol Gastrointest Liver Physiol, December 1, 1997; 273(6): G1233 - G1245. [Abstract] [Full Text] [PDF]