Chorda tympani nerve transection, but not amiloride, increases the KCl taste detection threshold in rats

Water-restricted rats were trained to press one lever after KCl presentatio n and the other lever after distilled water. Water reinforcement was given after each correct response, and a time-out followed each incorrect respons e. Rats were trained and tested on KCl stimuli of varying concentrations. T hreshold was defined as the KCl concentration corresponding to 1/2 the maxi mum asymptote of performance for each rat. The geometric mean KCl detection threshold for all rats was 0.033 M KCl. Rats that had the chorda tympani n erve (CT) bilaterally transected showed an average increase in KCl threshol d of approximately 0.60 log(10) units, whereas sham-operated rats showed no change. Control rats retested with 100 mu M amiloride added to all KCl con centrations and water displayed no change in threshold. These results sugge st that although the CT contributes significantly to the rat's sensitivity to KCl, amiloride-sensitive taste transduction pathways do not.