Figure 7.
Measurement of Cl- extrusion capacity at different developmental stages. A, Voltage-clamp recordings of a neuron presenting a monophasic outward current in response to a 20 ms application of GABA (triangle, left), whereas a 150 ms application (larger triangle, right) produces a biphasic current response. B, Estimated [Cl-]i based on Eanion measurements (see Materials and Methods) in whole-cell recorded neurons, with two high [Cl-] pipette solutions, at three developmental stages. There is a significant effect of age (p < 0.001) and pipette [Cl-](p < 0.001) on the resulting [Cl-]i (two-way ANOVA). In the presence of the KCC2 antagonist furosemide (Furo), the estimated [Cl-]i of P10-P11 and adult neurons was not different from that of the pipette solution (50 mm). Inset, Example of responses to 20 ms applications of GABA (triangles) obtained at different holding potentials (10 mV apart) of an adult neuron with 50 mm [Cl-] in the pipette.