Figure 4. K⁺-dependent gating is selective for permeant ions on the extracellular side.

A, recovery experiments as in Fig. 2B with 120 mm K⁺ on the intracellular side (K⁺_i) and 120 mm K⁺ (K⁺_o), Rb⁺ (Rb⁺_o), Cs⁺ (Cs⁺_o) or Na⁺ (Na⁺_o) in the recording pipette. Insets: K_ir1.1 single channel currents recorded from inside-out patches at −100 mV in symmetrical 120 mm K⁺ (left) and 120 mm Rb⁺ (right); single channel conductances were 32 ± 0.5 pS (n = 5) and 11 ± 0.7 pS (n = 6), respectively; closed level indicated by the dashed line. B, relative recovery of currents from experiments as in A (acidification periods of 50 s); bars represent means ±s.d. of 5-12 experiments.