Figure 1.

The voltage-dependent Na⁺ currents in HEK293t cells transfected with hH1_α, the α-subunit of the human cardiac Na⁺ channel. (A) Superimposed Na⁺ current traces were evoked by 10-ms duration depolarizing stimuli from −150, −120, and −90 mV to −30 mV at 0.2 Hz in an HEK cell expressing hH1_α Na⁺ channels. The decrease of the maximal Na⁺ current from −120 compared with −150 mV is very small. The inset shows that no I_Na,α was evoked by the same voltage steps in a HEK293t cell not expressing hH1_α Na⁺ channels. Capacitance and leakage currents have been subtracted on line from the Na⁺ currents shown. (B) The averaged peak I_Na,α was elicited by voltage steps to −30 mV from −150, −120, and −90 mV, respectively, in HEK293t cells expressing hH1_α (n = 27).