An analysis of residual NaCl taste response after amiloride.

The identity of the residual taste response to NaCl after lingual application of the sodium transport blocker, amiloride, was studied by electrophysiological recordings from the rat chorda tympani nerve. Stimulation of the anterior tongue with salt solutions resulted in responses to halogenated sodium salts that were not eliminated by amiloride; approximately 30% of the halogenated sodium salt response remained after amiloride. In contrast, responses to nonhalogenated sodium salts were reduced to less than 4% of the original response after amiloride. To further learn of characteristics relating to the residual NaCl response, binary mixture and cross-adaptation experiments were accomplished. Responses to mixtures of sodium acetate or sodium bicarbonate with choline chloride were similar to responses elicited by equimolar concentrations of NaCl before and after amiloride. Moreover, NaCl and NaBr cross-adapted with choline chloride after, but not before, lingual application of amiloride. These experiments indicate that the residual response to halogenated sodium salts (e.g., NaCl) is related to the halogen itself, and from findings presented here, we propose one pathway for sodium taste transduction.