Figure 5. Excitatory and inhibitory neurons have equivalent chloride extrusion capacity.
(A) Responses to 5–10 ms-long puffs of 1 mM GABA (arrowhead) were measured in voltage clamp at different holding potentials (inset) in neurons patched with a high-chloride (25 mM) pipette solution. Chloride reversal potential ECl, which corresponds to where the I-V curve intersects the x-axis, was measured before (black) and after (gray) blockade of KCC2 with 15 µM bath-applied VU. The shift in ECl reflects chloride extrusion capacity, which is not equivalent to the change in ECl caused by KCC2 blockade under natural conditions (i.e. without intracellular chloride loading). (B) Neurons identified as excitatory or inhibitory based on spiking pattern (inset) displayed no difference in chloride extrusion capacity (T12 = 0.030, p=0.98; unpaired T-test).