Regulation of colonic ion transort by gastrin releasing peptide:
ii. grp modulates the epithelial response to pge2.
Traynor, Tim R., and Scott M. O'grady.
Department of Physiology, University of Minnesota, Minneapolis,
Minnesota 55455; and Departments of Physiology and Animal Science,
University of Minnesota, St. Paul, Minnesota 55108
APStracts 2:0382C, 1995.
The purpose of this study was to examine the potential modulatory
effects of gastrin releasing peptide (GRP) on prostaglandin (PG) E2
-stimulated electrolyte transport across the distal colon epithelium.
In an earlier study, PGE2 was shown to reduce net Cl absorption
without altering the serosa-to-mucosa unidirectional Cl flux in
porcine distal colon (19). In the present study, tissues were
pretreated with serosal or mucosal GRP and subsequently stimulated
with PGE2. The resulting increase in Isc was 152% (serosal GRP) and
49% (mucosal GRP) greater than control PGE2 responses alone. Serosal,
but not mucosal, GRP also enhanced the Isc response to VIP. Based on
flux measurements the combined effects of serosal GRP and PGE2
resulted in the activation of a transcellular pathway for Cl
secretion which was not activated by either mediator alone. The time
course of the PGE2 response was also affected by GRP. Serosal GRP
shortened the time to maximum Isc by 35% while mucosal peptide
lengthened the time to max by 68%. These results suggest that GRP
acts as a modulator of prostaglandin action on electrolyte transport
in the distal colon.
Received 10 May 1995; accepted in final form 15 September 1995.
APS Manuscript Number C250-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95