Actions of calcitonin gene-related peptide (cgrp) in guinea pig
gallbladder ganglia.
Gokin[acute]a, Alexander G., Lee J. Jennings, and Gary M. Mawe.
Department of Anatomy and Neurobiology, The University of Vermont,
Burlington, VT, 05405; and Bogomoletz Institute of Physiology,
Academy of Sciences of Ukraine, Kiev, Ukraine, 252024
APStracts 3:0125G, 1996.
The actions of CGRP have been determined from intracellular recordings
obtained from gallbladder neurons in intact whole mount preparations.
In most cells, pressure microejection of CGRP elicited a slow,
monophasic depolarization, 4 mV in amplitude, that was associated
with a decrease in input resistance and increased excitability. The
CGRP-induced depolarization was attenuated in a low Na+ solution, and
had a reversal potential of -8 mV. In 10% of the cells, microejection
of CGRP elicited a biphasic response that comprised a rapid transient
depolarization followed by a slow depolarization that was similar to
the monophasic response. Addition of CGRP (1-10 nM) to the bathing
solution elicited a monophasic depolarization and desensitized the
cells to applications of CGRP by microejection. Forskolin, applied
either by microejection or bath application, also depolarized
gallbladder neurons, and produced cross-desensitization to CGRP.
Responses to substance P were not enhanced by CGRP, and CGRP did not
affect fast synaptic responses. It is concluded that CGRP may
contribute to a local axon reflex response in gallbladder ganglia.
Received 5 April 1995; accepted in final form 5 June 1996.
APS Manuscript Number G139-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 July 96