Figure 9. Measurements of GABA action on the cell membrane potential using cell-attached recordings.

A, a cell-attached record in response to a depolarizing ramp command (shown above the trace) from −140 to +200 mV (-V_pip). The holding potential (-V_pip) was −100 mV with respect to the cell membrane potential. Voltage-gated K⁺ currents activated by the depolarizing voltage ramp were initially inward, and then reversed to become outward. E_K was determined from the intersection of the fit (straight line) to the linear leak and the K⁺ current. The cell resting membrane potential was measured from the reversal of cell-attached K⁺ currents. B, plot of the cell membrane potential measured as shown in A against the recording time. GABA was pressure applied for 40 s as indicated by the bar. C, determination of K⁺ current reversal before and during GABA application (6 s after the start of the application).