Figure 5.

Determining the IFs and RCFs with intracellularly applied Cd²⁺. (A) An inside-out patch expressing T449A/V474C channels was exposed to 20 µM Cd²⁺ between P₁ and P₂ at −90 mV holding potential (top; see details also in Fig. 3) The holding potential before P₃ was −120 mV. Symbol × indicates a 30-ms-long pulse to −120 mV. Dashed reference lines are drawn to I₁, I₂, and I₃. (B) Based on the peak currents for each pulse, inactivated current fractions (IF = 1 − [I₂/I₁]) were calculated for the indicated holding potentials in the absence of Cd²⁺ (empty bars) or in the presence of 20 µM Cd²⁺ (hatched bars) or 200 µM Cd²⁺ (solid bars). (C) RCFs (RCF = [I₃ − I₂]/[I₁ − I₂]) were determined for the indicated holding potentials between P₁ and P₂ in the absence of Cd²⁺ exposure (empty bars) or in the presence of 20 µM Cd²⁺ (hatched bars) or 200 µM Cd²⁺ (solid bars) during the holding between P₁ and P₂. Data are given as mean ± SEM (n = 5); *, significant differences when P < 0.05 throughout the figure.