SODIUM-INTAKE LINKED TO AMILORIDE-SENSITIVE GUSTATORY TRANSDUCTION IN C57BL/6J AND 129/J MICE

Mice of 129/J and C57BL/6J inbred strains received two-bottle, 48-h preference tests of NaCl solutions vs. distilled water. 129/J mice exhibited a greater preference for 0.08 M NaCl than did C57BL/6J mice. To determine if this strain difference was mediated by taste, the integrated neural responses of the chorda tympani nerve to a concentration range of NaCl and KCl were examined. Gustatory neural responses to NaCl were similar for 129/J and C57BL/6J mice. However, lingual application of 0.5 mM amiloride hydrochloride significantly suppressed chorda tympani responses to a range of NaCl concentrations in C57BL/6J mice but did not do so consistently in 129/J mice. Amiloride failed to significantly suppress responses to a range of KCl concentrations in both mouse strains. The results suggest that for 129/J mice, sodium reception and transduction are primarily amiloride insensitive, whereas for C57BL/6J mice, both amiloride-sensitive and amiloride-insensitive components are present. The strain difference in NaCl intake may be mediated, in part, through gustatory mechanisms, with reduced preference for NaCl influenced by amiloride-sensitive sodium transduction mechanisms.