Fig. 8.

The effect of holding potential on reversal potential (E_rev) measured in 10 mM external SCN⁻. Families of whole cell currents evoked in a retinal pigment epithelial (RPE) cell from a holding potential (HP) of −120 mV (A), −60 mV (B), or 0 mV (C). Voltage-clamp protocols and current-voltage (I-V) plots of the instantaneous currents are shown in the insets on the bottom right and top right of each panel, respectively; the zero-current level is shown by the horizontal line to the left of currents. The interval between voltage steps was 20 s for HP = −120 mV or 15 s for HP = −60 mV and HP = 0 mV. The bath and pipette solutions contained high Cl⁻ concentrations. The effective series resistance after series resistance compensation was 2.5 MΩ. D: summary of similar experiments showing I-V plots of instantaneous current obtained from holding potentials of −120 mV (closed circles, n = 10), −60 mV (open circles, n = 6), and 0 mV (closed squares, n = 4). Symbols represent means and bidirectional error bars represent SE. E_rev shifted to more negative potentials as the holding potential was made more negative. Voltages are corrected for liquid junction potentials and the voltage drop across the series resistance. The data for HP = −60 mV are from a different set of experiments than that shown in Fig. 6C.