Figure 2.

Block of inward Na⁺ currents by external K⁺. All currents were recorded with 125 mM internal NMG⁺ and 155 mM external Na⁺. (A) Four sets of superimposed currents are shown, from four different channel types. Each set illustrates three inward currents, recorded in control (0K), after addition of 1 mM external K⁺ (1K) and after return to 0 mM K⁺. Currents were evoked by depolarization to 0 mV for the duration shown. (B) [K⁺]-dependent block of inward current in the four channel types. Data points represent the mean ± SEM of three to five cells.