Figure 4. Voltage dependence of amplitude and kinetics of I_BK and I_Kv.

A, normalized conductance–voltage (G–V) curves for I_BK (open circles) and I_Kv (open squares). Each point is the mean ±s.e.m. of 3–4 determinations in different cells normalised to the value at −10 mV. B, voltage dependence of the time constant of I_Kv activation (Kv_{activation τ}; filled squares), the time constant of I_BK inactivation (BK_{inactivation τ}; filled circles), the first time constant of I_BK activation (BK_{activation τ1}; upright open triangles), and the second time constant of I_BK activation (BK_{activation τ2;} inverted open triangles). Each point is mean ±s.e.m. of 3–4 determinations. Note logarithmic axis for τs. C, voltage dependence of ratio of steady-state I_BK current (average of I_BK over the last 100 ms of the 500 ms pulse) to peak I_BK. Each point is the average of 3–4 measurements in separate cells, except the leftmost point, which is a single determination. The dotted line is a linear fit to the data between −20 and +30 mV; its slope is 0.0078 mV⁻¹. The membrane potential axis is the same for all panels; the vertical dashed line denotes 0 mV.