Sodium taste detectability in rats is independent of anion size: The psychophysical characteristics of the transcellular sodium taste transduction pathway

There are two known sodium transduction pathways in the rat gustatory syste m. The transcellular pathway is blocked by amiloride, and the paracellular pathway is limited by the anion gluconate. The contribution of each pathway to sodium detection was assessed. Sodium gluconate (NaGlu) and NaCl thresh olds did not differ, implying that the paracellular pathway is not necessar y for normal sodium detection. Adding 100 muM amiloride raised both NaCl an d NaGlu thresholds but did not abolish all performance to NaGlu, indicating that some chemical cue was present at high concentrations. Rats were also exposed to one of three NaCl diets (0.12%, 1.0%, or 6.0% NaCl) through mate rnal and ad lib intake from Embryonic Day I through testing in adulthood. N o differences across dietary groups were found for NaCl or NaGlu threshold with or without amiloride. Thus, this developmental dietary treatment does not appear to affect taste sensitivity to sodium subserved through either t ransduction pathway. Collectively, these data suggest that the transcellula r transduction pathway is both necessary and sufficient for normal sodium d etection.