Effect of amiloride on suprathreshold NaCl, LiCl, and KCl salt taste in humans

The purpose of this study was to investigate normal variances in the response magnitudes of suprathreshold concentrations of NaCl, LiCl, and KCl salts and amiloride on the anterior human tongue. Random equimolar concentrations of salt solutions were delivered to spatially matched flow chambers of 20 volunteers at 3 different sessions. A cross-modal magnitude matching procedure was used to scale salt taste-intensity judgments. After each salt test, amiloride (100 microns) was delivered for 5 min and the test was repeated. At least-square regression analysis of each subjects' function between log molar concentration and log response demonstrated that every subject scaled the dynamic range of salts. There were no differences in either the mean regression or intercept among the 3 salts. Repeated-measures analysis demonstrated a statistical effect of amiloride on the before/after difference in the regression (p = 0.02) and intercept (p < 0.0001) of NaCl and LiCl functions. Postamiloride NaCl and LiCl coefficient of variance of response was increased. Amiloride had no effect on the before/after difference in the regression and intercept of KCl power functions or the variance of response. The results suggest that, after amiloride, NaCl and LiCl suprathreshold salt taste intensities are reduced, but there are individual variabilities of reduced intensity that are never completely eliminated.