Figure 5.

g_K,L , but not g_K,n, is Cs⁺ permeable. Left column: Currents in control conditions, with high internal K⁺ and 5.8-mM external K⁺. Middle column (different cells): With an internal Cs⁺ solution, g_K,n (B) carried only inward current but g_K,L (E) still passed both inward and outward current. Right column (same cells as middle column): When, in addition, external K⁺ was replaced with Cs⁺, all current through g_K,n was blocked (C; residual slope conductance = 600 pS) but outward current still flowed in the type I cell (F). Current and voltage axes on the left apply to all panels in a row. In standard solutions, relatively small voltage steps applied to the type I cell (D) elicited very large currents through g_K,L. Currents are from a P16 OHC (A), a P17 OHC (B,C), a P24 type I cell (D), and a P23 type I cell (E,F).