Figure 3.

Micromolar Ca²⁺ shifts Q–V and G–V curves. (A and B) Comparison of Q–V and G–V curves in the cell-attached mode and in 85 μM Ca²⁺ in the same cell. Data points were obtained and fitted as in Fig. 2. Dotted lines mark V½ values for Q–V curves. Fitted values were as follows: for cell-attached, V½ _{− G} = 137 mV, z_G = 1.4; V½ _{− Q} = 180 mV, z_Q = 0.6; for 85 μM Ca²⁺, V½ _{− G} = 35 mV, z_G = 1.5; V½ _{− Q} = 100 mV, z_Q = 0.7. (C) Corresponding gating current records in cell-attached mode (≈100 nM Ca²⁺) and after excision of the same patch in 85 μM free Ca²⁺. SHP = −120 mV. Solutions and pulse paradigms were as in Fig. 2.