The chorda tympani taste response of the rat to hydrochloric acid subject
to voltage-clamped lingual receptive field.
Desimone, John A., Esther M. Callaham, and Gerard L. Heck.
Department of Physiology, Virginia Commonwealth University, Richmond VA
23298-0551
APStracts 2:0026C, 1995.
The chorda tympani nerve response of the rat to HCl was obtained with the
lingual receptive field under voltage clamp. Unlike NaCl responses, HCl
responses were not affected by inside positive voltage perturbations.
However, HCl responses under negative voltage clamp were suppressed, in
contrast to NaCl responses which were enhanced. Unlike NaCl responses, HCl
responses were amiloride-insensitive. HCl rinsing from the tongue produced a
large off-response. At zero current clamp the off-response coincided with an
anomalous increased positive potential. The paracellular resistance was also
higher for HCl relative to the same concentration of NaCl. This is evidence
that H+ ions bind to the normally fixed anionic sites of the paracellular
pathway rendering it anion-selective. It is postulated that release of bound
H+ ion from surface buffer-sites is responsible for the second burst of
neural activity upon rinsing HCl. Acids stimulate primarily through the
paracellular pathway which also furnishes buffering sites that regulate H+
ion concentration, thereby protecting the sensory apparatus from hyperacidic
conditions.
Received 23 September 1994; accepted in final form 11 November 1994
APS Manuscript Number C0572-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.