Solutions
The intracellular solution was composed of 35 mM NaCl, 105 mM CsF, 10 mM EGTA, and 10 mM HEPES. The pH was adjusted to 7.3 with 2 M CsOH. The first external solution (Low Na+) was composed of 35 mM NaCl, 115 NMDG, 2 mM KCl, 1.5 mM CaCl2, 1 mM MgCl2, 10 mM glucose, and 10 mM HEPES. The pH was adjusted to 7.4 with 2 M HCl. The second external solution (Full Na+) used to record persistent Na+currents was composed of 150 mM NaCl, 2 mM KCl, 1.5 mM CaCl2, 1 mM MgCl2, 10 mM glucose, and 10 mM HEPES. The pH was adjusted to 7.4 with 2 M HCl. TTX (LATOXAN, Portes-lès-Valence, France) was diluted to 75 𝛍M in 2% acetic acid.