Figure 6.

Block of Na⁺ gating pore currents in R666G by trivalent cations Gd³⁺, Yb³⁺, and La³⁺. (A) Representative gating pore currents recorded in 120 mM Na⁺, 1.8-mM Ca²⁺ external solution (left, black traces), and after addition of 5 mM GdCl₃ (top right), 5 mM YbCl₃ (middle right), or 5 mM LaCl₃ (bottom right). (B) Concentration dependence of Gd³⁺ block at either 0-mV holding potential (black circles; IC₅₀ = 207 ± 10 µM, n = 4–6) or −80-mV holding potential (red triangles; IC₅₀ = 238 ± 14 µM, n = 3–6). (C) Normalized leak-subtracted current-voltage relationships for Na⁺ gating pore currents recorded with a −80-mV holding potential in control 1.8Ca external solution (black circles, n = 5) and in the presence of 500 µM Gd³⁺ (red triangles, n = 4). Error bars represent SEM.