Figure 2.
L-type calcium and KCa3.1 potassium channels functionally couple. A, B, Whole-cell currents of CaV1.2 (A) and CaV1.3 (B) calcium channels expressed in tsA-201 cells exhibit pronounced calcium-dependent inactivation. CaV1 channels were coexpressed with α2δ1 and β1b accessory subunits. Coexpression of KCa3.1 channels with CaV1.2 (A) or CaV1.3 (B) result in an inward Ca2+ current followed by KCa3.1-mediated potassium current. C, The current–voltage plots for KCa3.1 channels closely follow the voltage dependency of corresponding CaV1 calcium channel isoforms. Outward currents were evoked from a holding potential of −70 mV and measured at 1 s. D, E, Representative traces of KCa3.1 currents blocked by internal perfusion of 1 μm TRAM-34 (D) or 5 mm EGTA (E) over a 5–7 min time period. Numbers of cells are denoted in brackets in C.