Figure 5.

Time course of BP block of BK channels in K⁺ and Rb⁺ solutions. Raw currents at the indicated potentials in the absence (black) and presence (red) of 2 µM BP recorded in 100 µM Ca²⁺ in K⁺ (left; calibration: 1.2 nA, 50 msec) and Rb⁺ (right; calibration: 0.25 nA, 50 msec) solutions. The holding potential for the K⁺ solutions was −80 mV. For the Rb⁺ solutions, the voltage level before depolarization was −100 mV, and after the depolarization it was −80 mV. The tail currents upon repolarization have been truncated for clarity.