Figure 8. Effect of low concentrations of ${\text{K }}_{\text{o}}^{+}$ on outward Na⁺ currents through Kv1.5 channels.

In all cases control solutions were 130 mM ${\text{N }}_{\text{i}}^{+}$/5 mM ${\text{N }}_{\text{o}}^{+}$. A-E, current traces showing effect of addition of different extracellular K⁺ concentrations. The control trace is labelled 0 mM ${\text{K }}_{\text{o}}^{+}$. Data were obtained at +60 mV, pulses were at 0.05 Hz. Dotted lines denote zero currents. F, relationship between normalized peak Na⁺ conductance in different added ${\text{K }}_{\text{o}}^{+}$. Plotted points are from a mean of 4–12 cells in each case. From the Hill fit to data points, for added ${\text{K }}_{\text{o}}^{+}$, the K_d was 0.08 ± 0.01 mM and n_H was 0.9 ± 0.1.