Physicochemical studies of taste reception. I. Model membrane simulating taste receptor potential in response to stimuli of salts, acids and distilled water.

Abstract A Millipore filter paper impregnanted with the lipids extracted from bovine tongue epithelium was used as a model for the taste receptor membrane and the membrane potentials arisen between two solutions across the membrane were measured under the presence of salts, acids and distilled water as taste stimuli. The changes in the membrane potential induced by these stimuli paralleled closely the taste receptor potentials observed intracellularly with living taste cells or taste never responses as shown in the following. 1. 1. Various salts carrying a common species of anion (NaCl, KCl, NH4CL and CaCl2) at a given concentration induced a different magnitude of potential deflections, while sodium salts carrying different species of anion (NaF, NaCl, NaBr and NaI) induced a practically identical potential deflection. The relationship between the magnitude of the potential deflection and the NaCl concentration followed the taste equation. The potential deflection induced by the application of a given concentration of NaCl was independent of pH in a wide range of pH between 3 and 12. 2. 2. A treatment of the membrane with FeCl3 brought about a reversal of the polarity of the steady potential. An application of NaCl to the FeCl3-treated membrane induced a variation of the potential deflection with a polarity opposite to that normally displayed. 3. 3. The relations between pH and the magnitude of the potential deflection induced by HCl and acetic acid closely resemble those derived from th taste nerve responses. 4. 4. The model membrane showed potential deflections corresponding to the “water response”; an application of distilled water to the membrane adapted with tap water, Ringer solution, CaCl2 or NaCl solution brought about a potential deflection as if a high concentration of chemicals were applied to the membrane.