The Role of Tight Junctions and Hypertonicity in Taste Information Processing

Many scientists have investigated taste nerve responses without regarding the tonicity of taste stimulating solutions that varies in a wide range. We increased the tonicity by adding nonelectrolytes that elicited no taste nerve responses in bullfrogs, and investigated hypertonicity effects on the taste nerve responses to inorganic salts and bitter substances. Here, we show that the hypertonicity opens tight junctions surrounding taste receptor cells and changes the magnitude and firing pattern of taste nerve responses. We quantitatively suggest that the changes result from the magnitude and direction of local circuit currents generated by diffusion potentials across the tight junctions.