Responses of the proton currents to temperature pulses (pH_i/pH_o, 5.5/7.3). (A) Proton currents were elicited by depolarizing steps to 0 mV (inset; the voltage command with the holding potential of −80 mV). Temperature pulses (blue lines; duration, 1 s) were applied during the steady state of the gating activation. Current amplitudes were measured immediately before and after the onset (red arrows) and termination (blue arrows) of the pulses. The depolarizing pulses were followed by hyperpolarizing ramps (20 ms), and the outward tail currents were not obvious in these traces. (B) Temperature pulses were applied at the hyperpolarizing potential of −100 mV.