Intercellular metabolic coupling in canine colon musculature.
Farraway, Laura, Alexander K. Ball, Jan D. Huizinga.
Intestinal Disease Research Unit, Department of Biomedical Sciences,
McMaster University, Hamilton, Ontario, Canada L8N 3Z5
APStracts 2:0042C, 1995.
Intercellular communication within the musculature of the canine colon was
studied by examining the results of neurobiotin diffusion following injection
of the tracer into smooth muscle cells at different locations within the
muscle layer. Circular muscle at the submucosal surface, circular muscle
adjacent to the myenteric plexus, and longitudinal muscle, demonstrated
different degrees of time dependent tracer spread. At the submucosal surface,
tracer spread was rapid, extensive and unimpeded by connective tissue septa.
At the myenteric side, tracer spread was also extensive but was much slower
and confined to bundles of cells bordered by septa. In contrast to previous
studies which suggest an absence of gap junctions in the circular muscle, the
neurobiotin spread at the myenteric side indicates full metabolic coupling of
all neighbouring muscle cells. Furthermore, in contrast to the belief that
longitudinal muscle is completely devoid of gap junctions, tracer spread
occurred between cells in this layer although neurobiotin diffusion was very
limited, non-uniform and slow. In each area of the musculature studied,
tracer spread was inhibited by octanol. When very long injection and wait
times were implemented at the submucosal surface of the circular muscle,
neurobiotin was observed to cross septa through the network of interstitial
cells of Cajal indicating that it is this network that provides communication
between lamellae.
Received 4 March 1994; accepted in final form 30 November 1994
APS Manuscript Number C0118-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.