Effects of local anesthetics on frog taste cell responses.

Abstract

Immediately after application of procaine or lidocaine to the surface of the tongue a transient response occurs in the glossopharyngeal nerve, while a depolarization of a few mV associated with an increase in the input resistance was observed in taste cells. When applied to the tongue for a long time, procaine and lidocaine depressed responses in the glossopharyngeal nerve to chemical stimulation of the frog tongue. The depressant effect is strongest on quinine response, next on responses to salts, and weakest on response to acid. Under the action of the local anesthetics both the magnitude of depolarization and the amount of input resistance change in taste cells, produced by stimulation by various chemicals, are small compared with those observed in normal cells. The action of anesthetics on the depolarization in taste cells is also strongest on quinine response and weakest on acid response. The results indicate that the local anesthetics exert a depressant action on taste cells by inhibiting changes in the membrane conductance and generation of depolarization, which are produced by chemical stimuli and are responsible for impulse initiation at sensory nerve terminals.