Figure 10.

Cell-attached patch recording of W434F channels with 140 mM K⁺ pipette solution. (A) Mean current (predominantly gating current) in response to depolarization to +80 mV from −80 mV holding potential; the average of 100 sweeps is shown. The patch contained 2,400 channels, as estimated from the integrated gating current assuming 13 e₀ of charge movement per channel. P/5 leak subtraction was used with a leak holding potential of −120 mV. (Contamination of gating current during the P/5 pulse produces the artifact preceding the “off” current.) Data were filtered at 5 kHz. (B) Six of the 164 sweeps with detectable ionic currents, selected from a total of 1,400 sweeps recorded. Data were filtered at 3 kHz and are displayed after subtraction of the mean of 100 sweeps to remove gating and leak currents. (C) Time course of open probability estimated from idealization of the sweeps containing channel activity. The superimposed curve is an exponential function with 1 ms time constant. The pipette solution contained (in mM) 140 K-aspartate, 1.8 CaCl₂, 10 HEPES, pH 7.4.