AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 2 394-R402, Copyright © 1989 by American Physiological Society
Activation by saccharides of a cation-selective pathway on canine lingual epithelium
S. A. Simon, P. Labarca and R. Robb
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710.
Responses of isolated canine lingual epithelium in an Ussing chamber to
D-glucose and fructose reveal events associated with taste transduction.
With the use of isotopic flux studies, together with ion substitution and
pharmacological and voltage clamp measurements, it was found that the
stimulation of ion transport by D-glucose arises from an increase in the
influx of cations through a cation-selective pathway. This influx of
cations is completely inhibited by 0.1 mM amiloride. The stimulation of
transport by fructose in 0.05 M KCl and by D-glucose in 0.05 M RbCl was
also inhibited by amiloride, demonstrating that the saccharide-stimulated
entry pathway was specific for neither hexose sugars nor for Na. Saccharide
stimulation of canine lingual epithelia does not appear to be modulated by
increases in intracellular levels of adenosine 3',5'-cyclic monophosphate,
guanosine 3',5'-cyclic monophosphate, or Ca. The Na that enters taste cells
on saccharide stimulation exits them via the ouabain inhibitable
Na+-K+-adenosinetriphosphatase located in the serosal membranes.
