Figure 1.

Na⁺ permeation through hERG potassium channels. (A) Na⁺ currents were elicited by depolarizing voltage steps from hERG channels stably expressed in HEK 293 cells. The pipette solution contained 135 mM Na⁺ and the bath solution contained 135 mM NMG⁺ as major cations. (B) Na⁺ currents recorded from the hERG-HEK 293 cells were completely blocked by 1 μM astemizole, a specific hERG blocker. (C) No Na⁺ current could be detected in the nontransfected HEK 293 cells. (D) Current–voltage (I-V) relationships for the peak (▴) and steady-state (•) hERG Na⁺ currents recorded during the 4-s depolarization pulses (n = 13, data points and error bars signify mean ± SEM).