Figure 3. IK1 channels are functionally expressed in U251 glioma cells.

(A) Representative recordings of the whole-cell IK1 currents elicited by depolarization step pulses from −120 mV to +80 mV in 20 mV intervals. Whole cell IK1 currents were activated by clamping pipette [Ca²⁺] at 750 nM. To prevent concomitant activation of BK currents, 2 µM paxilline was added into bath solution. (B) In the same cell shown in (A), the whole cell IK1 currents were inhibited by the potent IK1 blocker clotrimazole (2 µM). (C) Whole cell currents in response to depolarization ramps from −120 mV to +80 mV in the absence or presence of clotrimazole. (D–F) Results of similar experiments employing the selective IK1 blocker TRAM-34 (1 µM).