NaCl detection thresholds: Comparison of Fischer 344 and Wistar rats

Adult Fischer 344 (F344) rats fail to display any preference for NaCl solut ions at concentrations typically preferred by other rat strains. To determi ne whether this behavior is due to a strain difference in NaCl detection th reshold, a conditioned taste aversion (CTA) was first established to a supr athreshold concentration of NaCl (0.1 M). Then, a series of dilute NaCl sol utions, ranging from 0.0 to 0.011 M NaCl, were presented to F344 (n = 16) a nd Wistar (n = 16) rats. The lowest concentration at which there was a reli able difference in the preference scores of conditioned and control rats wa s defined as the detection threshold. Results indicate that the detection t hreshold for NaCl lies between 0.001 and 0.002 M NaCl for both F344 and Wis tar rats. The addition of the sodium channel blocker amiloride to the NaCl solutions raised the detection threshold 10-fold to 0.03-0.04 M NaCl for bo th strains of rats. These results suggest that the NaCl detection threshold s of F344 and Wistar rats are similar and that these strains do not differ in the degree to which amiloride raises this threshold.