Figure 2.

“Cl_i load”: quantification of outward Cl⁻ transport after dendritic Cl⁻ influx raises Cl_i. The cell was recorded with 9 mm Na_pipette. A, To raise dendritic Cl_i, V _m was stepped to −5.5 mV for 1 s; 200 ms into the depolarizing voltage step, GABA was applied to the dendrites to elicit a large inward Cl⁻ flux. V _m was then stepped to −68.5 mV (2.6 mV negative to steady-state E _Cl), and a second GABA puff evoked a “test” current. As in Figure 1 B, six trials of paired GABA puffs were performed, each with a different delay between Cl_i load and the test current. B, As the interval between the Cl_i load and test current increases, the charge transfer of the test currents returns to steady state. C, Cl_i is calculated from the shift in E _Cl that accounts for the direction and charge transfer of each test current. Fit lines in B and C are single exponentials (Eq. 4).