Fig. 1.

Shift of voltage-dependent activation of transient delayed-rectifier K⁺ currents in guinea pig airway smooth muscle cells (ASMCs) by Gd³⁺. A: representative current (I) traces recorded during the first 500 ms of 5-s voltage steps at −60, −20, 0, and +20 mV as indicated in control (left) and in the presence of 100 μM GdCl₃ (right). B: current-voltage (V; I-V) relationships of peak K⁺ currents recorded in ASMCs before (control, ●, n = 3), after 10-min treatment with 100 μM GdCl₃ (○, n = 3), and after washout of GdCl₃ for 10 min (▴, n = 3). C: averaged fractional conductance plots calculated from peak K⁺ currents measured in ASMCs in control (●) and in the presence of 100 μM GdCl₃ (○) and after washout of 100 μM GdCl₃ (n = 3) fitted to a Boltzmann distribution [voltage of half-maximal activation (V_0.5) = 7.3 ± 1.8 mV in control, V_0.5 = 20.5 ± 1.5 mV in the presence of 100 μM GdCl₃, V_0.5 = 10.4 ± 1.0 mV after washout of 100 μM GdCl₃, n = 3]. G/G_max, the fraction of maximal conductance. *Significant difference from control, P < 0.001, 1-way ANOVA.