Ionic Mechanisms of the Resting Potential and Quinine-Induced Receptor Potential in Frog Taste Cells

Abstract

This chapter describes the ionic bases of the taste cell resting potential and the mechanisms by which bitter stimuli induce changes in the membrane potential. It shows the effects of replacing the normal superficial fluid covering the tongue with various modified saline solutions on the receptor potentials elicited by 10 mM Q-HCI. When ions other than HEPES buffer were removed from the superficial fluid, the amplitude of the depolarizing receptor potentials produced by Q-HCI increased to 200% of control responses. One way to study the initial transformation of a taste stimulus into change in receptor cell membrane potential is to record stimulus-evoked changes in electrical activity from single taste cells. Recently, ionic currents of various types have been inferred in Necturus taste cell membranes using intracellular recordings and ion substitution and pharmacological agents. These currents have been confirmed in several species using whole-cell and single-channel patch-clamp recordings from isolated taste cells.