Strain differences in taste reactivity to NaCl.

The taste reactivity test was used to determine whether strain differences in response to NaCl revealed by preference tests were attributable to taste or postoral factors. Taste reactivity data revealed significant differences between sodium-replete Fischer 344 (F-344) and Wistar strains in response to NaCl for both aversive and ingestive oral motor behaviors. Because the taste reactivity test analyzed the immediate response to orally applied chemical stimuli, these data support a strain difference based on taste factors. Taste reactivity data also indicate strain differences in ingestive but not aversive scores to other normally ingested chemical stimuli, water, and two sucrose concentrations. In response to normally avoided quinine, F-344 and Wistar strains did not differ in either ingestive or aversive score. To investigate whether strain differences revealed when rats were tested while sodium replete would persist in the sodium-deficient state, both strains were treated with the diuretic furosemide. Taste reactivity tests revealed that in response to sodium deficiency both F-344 and Wistar strains shift their oral motor response profile to NaCl; strains did not differ in either ingestive or aversive score when sodium deficient. NaCl intake and preference measures also support the fact that both strains demonstrate a sodium appetite. Interpretive limitations based on ceiling and floor effects within taste reactivity and preference data were discussed.