Response characteristics of rat taste cells to potassium benzoate.

The rat taste cells responded to K-benzoate solutions higher than the threshold concentrations (0.03-0.3 M) with a depolarizing receptor potential, but they responded to K-benzoate lower than the thresholds with a hyperpolarizing receptor potential. In either depolarizing or hyperpolarizing receptor potentials the rise time decreased with increasing amplitude, but the fall time increased with increasing amplitude. During generation of either depolarizing or hyperpolarizing receptor potentials the input resistance of taste cells decreased with increasing amplitude. Application of the mixtures of various concentrations of NaCl and 0.05 M K-benzoate resulted in a reduction of receptor potential amplitude, as compared with that evoked by application of NaCl alone. It is concluded that a depression of gustatory neural impulse frequency by low concentrations of K-benzoate is mainly due to the hyperpolarizing receptor potential of taste cells elicited by the K-benzoate solutions.