Cationic and anionic channels of apical receptive membrane in a taste cell contribute to generation of salt-induced receptor potential

• 1.1. After ionic composition of superficial fluid (ISF) and interstitial fluid (ISF) of the frog Rana catesbeiana) tongue had mostly been changed with a low Na⁺ saline solution, the relations between membrane potentials and receptor potentials in a frog taste cell evoked by various concentrations of NaCl and various types of salts were analyzed to examine permeability of the taste receptive membrane to cations and anions.
• 2.2. The mean reversal potentials for depolarizing potentials of a taste cell in response to 0.05 M, 0.2 M and 0.5 M Nad were -40.0, 6.4 and 28.8 mV, respectively.
• 3.3. When adding an anion channel blocker, SITS, to a NaCl solution the reversal potential for receptor potential with NaCl plus SITS became about twice as large than with NaCl alone.
• 4.4. Reversal potentials for 0.2 M NaCl, LiCl, KCl and NaSCN were 6.4, 25.4, −1.0 and −7.8 mV, respectively, indicating that permeability of the apical taste receptive membrane to cations of Cl⁻ salts is arranged in the order of Li⁺ > Na⁺ > K⁺ and that the permeability to anions of Na⁺ salts is arranged as SCN⁻ > Cl⁻
• 5.5. It is concluded that in the case of NaCl stimulation, Na⁺ and Cl⁻ of NaCl stimulus permeate NaCl-gated cationic and anionic channels at the apical taste receptive membrane in generating receptor potentials.