Action potentials were recorded with current-clamp whole-cell configuration. The pipette solution for current-clamp experiments contained (in mM): 123 K-gluconate, 10 KCl, 1 MgCl2, 10 HEPES, 1 EGTA, 0.1 CaCl2, 1 K2ATP, 0.2 Na4GTP and 4 glucose, pH adjusted to 7.2 with KOH. Membrane potentials were kept around −65 to −70 mV, and step currents were injected to elicit action potentials. For whole-cell voltage dependent current recordings, the same internal solution as aforementioned was used. For synaptic functional evaluation, the internal solution contained (in mM): CsCl 135, HEPES 10, EGTA 1, Mg-ATP 4, Na4GTP 0.4, and QX-314 10, pH7.4. The bath solution contained (in mM): NaCl 140, KCl 5, CaCl2 2, MgCl2 2, HEPES 10, and glucose 10, pH7.4. Synaptic responses were measured as described previously13,25. Stimulus artifacts for evoked synaptic responses were removed for graphic representation. Electrophysiological data are presented as mean ± SEM. All statistical comparisons were made using Student’s t-test.
