Electrophysiological effects of cholinergic agonists in surface
epithelium of necturus gastric antrum.
Gadacz, Audrey E., Mary E. Klingensmith, and David I. Soybel.
Department of Surgery, Brigham and Women's Hospital and Harvard
Medical School, Boston, Massachusetts, 02115
APStracts 2:0204G, 1995.
Intracellular microelectrode techniques were used to characterize
voltage and conductance properties of the basolateral membrane of
surface epithelial cells in in vitro Necturus antral mucosa. Flux
studies confirmed that this tissue secretes HCO3- under resting
conditions and during response to cholinergic stimulation. In studies
using intracellular microelectrodes, exposure to cholinergic agonists
such as acetylcholine (ACh), bethanechol (BCh), or carbachol (CCh)
elicited an initial hyperpolarization followed by depolarization of
the basolateral cell membrane, associated with up to 4-fold increases
in basolateral membrane conductance. Effects of ACh were dose
-dependent (from 10-6 to 10-4M) and prevented by pre-treatment of
tissues with the non-selective muscarinic receptor blocker, atropine.
Some variations in this response to cholinergic stimulation was
observed and appeared to be related to the season (fall/winter/early
spring versus late spring/summer). Despite such variability, circuit
analysis and ion substitution studies indicated that the CCh-induced
increases in basolateral conductance were due to increases in
conductance to both K+ and Cl-. These increases in basolateral
transport processes may serve to stabilize cell ion composition and
membrane electrical properties during cholinergic stimulation of
mucus and HCO3-
Received 7 February 1995; accepted in final form 20 September
1995.
APS Manuscript Number G53-5.
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