Fig. 2.

L-WNK1 expression increases whole cell BK channel activity. HEK293 cells were transfected with BK α-subunit alone or with L-WNK1. Patch-clamp studies were performed with the amphotericin B perforated whole cell technique (A–C) or with conventional whole cell patch-clamp (D), as described in materials and methods. BK currents were evoked by voltage steps from −80 to 100 mV in 10-mV increments from a holding potential of −60 mV (A–C) or by voltage steps from −80 to 200 mV in 20-mV increments from a holding potential of −80 mV (D). A and B: representative tracings obtained in the absence or presence of 100 nM iberiotoxin (IBTX) from cells transfected with myc-tagged BK α-subunit alone (A) or with L-WNK1 (B). C: summary of the effect of L-WNK1 on IBTX-sensitive whole cell currents measured at +80 mV (n = 6–7, *P < 0.01) (Student's t-test). D: normalized steady-state conductance-voltage (G–V) relationships for cells transfected with BK α-subunit alone (open circles) or with L-WNK1 (closed circles) (n = 9–11). Data were fitted to a Boltzmann function as described in materials and methods.