Amiloride-Sensitive and Amiloride-lnsensitive Responses to NaCI + Acid Mixtures in Hamster Chorda Tympani Nerve

摘要

Component signaling in taste mixtures containing both beneficial and dangerous chemicals depends on peripheral processing. Unidirectional mixture suppression of chorda tympani (CT) nerve responses to sucrose by quinine and acid is documented for golden hamsters (Mesocricetus auratus). To investigate mixtures of NaCI and acids, we recorded multifiber responses to 50 mM NaCI, 1 and 3 mM citric acid and acetic acid, 250 μM citric acid, 20 mM acetic acid, and all binary combinations of each acid with NaCI (with and without 30 nM amiloride added). By blocking epithelial Na~(+) channels, amiloride treatment separated amiloride-sensitive NaCI-specific responses from amiloride-insensitive electrolyte-generalist responses, which encompass all of the CT response to the acids as well as responses to NaCI. Like CT sucrose responses, the amiloride-sensitive NaCI responses were suppressed by as much as 50% by citric acid (P = 0.001). The amiloride-insensitive electrolyte-generalist responses to NaCI + acid mixtures approximated the sum of NaCI and acid component responses. Thus, although NaCI-specific responses to NaCI were weakened in NaCI-acid mixtures, electrolyte-generalist responses to acid and NaCI, which tastes KCI-like, were transmitted undiminished in intensity to the central nervous system. The 2 distinct CT pathways are consistent with known rodent behavioral discriminations.