Figure 3.

Isochronal activation. A single 10 ms depolarizing pulse from the holding potential of −90 mV was applied in 10 mV steps to potentials from −100 to +80 mV, followed by a step to −50 mV. Representative traces are shown from (A) Kv1.4, (B) Kv1.4ΔN, (C) Kv1.4[P558G], and (D) Kv1.4[P558G]ΔN. Isochronal activation calculated as the peak current measured on repolarization to −50 mV for (E) Kv1.4 (■, n = 4) and Kv1.4[P558G] (●, n = 10, error bars smaller than symbols), and (F) Kv1.4ΔN (■, n = 5) and Kv1.4[P558G]ΔN (●, n = 9, error bars smaller than symbols). Solid lines are Boltzmann fits to data 1/(1+exp((V−V_1/2)/k)).