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The Biophysical Journal





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Under an Elsevier user license

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February 2015



We have measured the NaCI or KCI currents under voltage clamp across the dorsal lingual epithelium of the rat and simultaneously the response of the taste nerves. Under short-circuit conditions a NaCI stimulus evoked an inward current (first current) that coincided with excitation of the chorda tympani. This was followed by a slower inward current (second current) that matched the kinetics of taste nerve adaptation. The peak first current and the coincident neural response satisfied the same saturating NaCI concentration dependence. Both first and second currents were partially blocked by amiloride as were the phasic and tonic components of the neural response. The NaCI-evoked second current was completely blocked by ouabain. Investigation of the NaCI-evoked current and the neural response over a range of clamped voltages showed that inward negative potentials enhanced the inward current and the neural response to 0.3 M NaCI. Sufficiently high inward positive potentials reversed the current, and made the neural response independent of further changes in voltage. Therefore, one of the NaCI taste transduction mechanisms is voltage dependent while the other is voltage independent. A KCI stimulus also evoked an inward short-circuit current, but this and the neural response were not amiloride-sensitive. The data indicate that neural adaptation to a NaCI stimulus, but not a KCI stimulus, is mediated by cell Na/K pumps. A model is proposed in which the connection between the NaCI-evoked second current and cell repolarization is demonstrated.


From The Biophysical Journal, Heck, G.L, Persaud, K.C., and DeSimone, J.A., Direct measurement of translingual epithelial NaCl and KCl currents during the chorda tympani taste response, Vol. 55, Page 843. Copyright © 1989 The Biophysical Society. Published by Elsevier Inc. Reprinted with permission.

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VCU Physiology and Biophysics Publications