Whole-Cell Patch-Clamp Electrophysiology

Cells were patch-clamped in whole-cell mode using Cs⁺-filled pipettes as previously described^{35 (link)}. The following ion channel modulators were used: Tetraethylammonium chloride (TEA, T2265, Sigma-Aldrich) to block dominant BK channels, Nifedipine (N7634, Sigma-Aldrich) to inhibit Ca_V1.3 channels, Bay K 8644 (1544, Tocris) to activate Ca_V1.3 channels and Mibefradil (2198, Tocris) or NiCl₂ (Ni²⁺) to block Ca_V3.2 channels. Nifedipine and Bay K 8644 were prepared as stocks in DMSO and diluted so that the final vehicle concentration was < 0.1%. Cs⁺-pipette solution comprised (mM): 110 CsCl, 20 TEA-Cl; 5 MgCl₂; 1 EGTA; 0.1 Na₂GTP; 2.5 Na₂phosphocreatine; 4 Mg-ATP; 5 HEPES, 296.8 mOsm/L, pH 7.2. TEA-Ba²⁺ PSS comprised (mM): 115 NaCl, 10 TEA-Cl, 1 MgCl_2, 5.5 Glucose, 10 BaCl₂, 10 HEPES, 298.5 mOsm/L, pH 7.4. Divalent-free PSS comprised (mM): 129.8 NaCl, 5.4 KCl, 10 glucose, 2.9 sucrose, 4.2 NaHCO₃, 0.4 KH₂PO₄, 0.3 NaH₂PO₄, 5 EGTA, 10 HEPES, osmolarity 308.1 mOsm/L, pH 7.4.