Figure 9.

ShH4 ionic current evoked by a 40-ms depolarizing pulse to 20 mV, just before and after 24 min of internal perfusion of an oocyte with NMDG-Glu (400 μl/h). The traces are scaled to the peak current, with amplitudes indicated next to the corresponding trace. In this cell, ionic current decayed with a time constant of 4.3 ms at the beginning of the experiment, and of 3.3 ms 24 min later, as the peak current was only 5% of the initial one. The perfusion pipette was placed close to the cytoplasmic face of the dome membrane. The current was monitored every 5 s, from a HP = −90 mV. The top and guard solution was NaMES Ca2, the bottom and perfusion pipette solution was NMDG-Glu. The data were sampled at 10 kHz and filtered at 2 kHz. A P/−4 protocol from SHP = −90 mV was used for leak subtraction.