Selective stimulation of epithelial cells in colonic crypts:
relation to active chloride secretion.
Halm, Dan R., Susan T. Halm, Donald R. Dibona, Raymond A. Frizzell,
Rodney D. Johnson.
Department of Physiology, Ohio State University, 1645 Neil Avenue,
Columbus, OH 43210, Department of Marine Biomedical and Environmental
Sciences, Medical University of South Carolina, 221 Fort Johnson
Road, Charleston, SC 29412, Department of Physiology & Biophysics,
University of Alabama at Birmingham, Birmingham, AL 35294, United
States Environmental Protection Agency, 6201 Congdon Boulevard,
Duluth, MN 55804
APStracts 2:0169C, 1995.
Stimulation of Cl secretion by prostaglandin-E2 was measured as the
short-circuit current (Isc) across isolated epithelium of the rabbit
distal colon. Cellular morphology of columnar and goblet cells during
secretion was monitored using light and electron microscopy.
Stimulation by PGE2 altered epithelial cell morphology only by a
reduction of vacuolar space in the apical pole of crypt columnar
cells, consistent with release of vacuole contents. Imaging of
isolated crypts using differential interference microscopy confirmed
the release of material from columnar cells during the onset of
secretion. Inhibition of Cl secretion with the loop-diuretic
bumetanide did not block vacuole release. The actin filament
disrupting agent cytochalasin reduced the PGE2-stimulated Isc by 40
per cent and blocked emptying of the vacuolar space. These electrical
and morphological results indicate that the process of active ion
secretion is associated with release of the macromolecular contents
from apical vacuoles through a mechanism involving the cytoskeleton.
In addition, this relationship supports the concept that vacuolated
-columnar cells of the crypts of Lieberk[umlaut]uhn are the cell type
that secretes Cl in response to PGE2.
Received 21 December 1994; accepted in final form 11 April 1995.
APS Manuscript Number C732-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.