Potassium and chloride currents in rat gastric enterochromaffin
-like cells.
Loo, Donald D. F., George Sachs, and Christian Prinz.
Department of Physiology, UCLA School of Medicine, Center For the
Health Sciences, Los Angeles, CA 90095-1751, and Center for Ulcer and
Research and Education, Digestive Disease Center, Veterans
Administration, West Angeles Medical Center, Los Angeles, CA
90073
APStracts 2:0205G, 1995.
The gastric enterochromaffin-like (ECL) cell secretes histamine in
response to secretagogues (gastrin, acetylcholine) by calcium
signaling dependent exocytosis of intracellular vacuoles containing
the hormone. ECL cells were isolated from rat fundic gastric mucosa
by elutriation and density gradient centrifugation. Currents across
the plasma membrane were measured using whole cell patch clamp
methods. These cells had a low conductance of 0.5 nS, and resting
potential of -50 mV. Depolarization activated a K+ current, that was
blocked by Ba2+. Steady-state current in absence of K+ was due to Cl-
because of the magnitude of the reversal potential and the effects of
Cl- removal. Stimulation of secretion by gastrin, CCK-8 and the
phorbol ester TPA, activated the Cl- conductance with a time course
similar to that of histamine release. Therefore the ECL cell
maintains a high resting potential, largely due to K+ currents and
stimulation of secretion activates a Cl- current perhaps deriving
from the membrane of the secretory granule that fuses with the plasma
membrane. The depolarization that ensues may activate the K+ current
to maintain the membrane potential during exocytosis.
Received 31 July 1995; accepted in final form 2 October 1995.
APS Manuscript Number G322-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95