Dual-patch clamp from hippocampal astrocyte reveals the voltage error that accounts for the shift in reversal potential of the Ca2+-activated anion conductance. A. DIC Image of single hippocampal astrocyte loaded with SR101, with two electrodes sealed on the cell somata. Scale bar: 10 μm. B. The whole cell current recorded from the right electrode and real membrane potential recorded from the left electrode. Command voltages were stepped from -140 mV to +40 mV with an increase of 20 mV. The holding potential was -60 mV. C. The ramp currents recorded from the right electrode and actual membrane potential recorded from the left electrode (Average of 5 sweeps). Ramp protocol was given from +100 mV to -100 mV. D. The representative I-V relationship of subtracted current between before and during NPPB application represents NPPB sensitive current.