Inhibition of Ca_V3.2 by 20 μM Ni²⁺. (A) Sample currents with the IIV protocol. Cell d080508, 3-kHz Gaussian filter. (B and C) IIV relationships for inhibition by Ni²⁺ in 2 mM Ca²⁺ (n = 7) and 2 mM Ba²⁺ (n = 4). Prepulses to +60 mV were 2 ms or 3 ms in different cells. (D and E) Ni²⁺/control ratios, calculated from chord conductances, from IIV and I-V protocols (see Figs. S8 and S9). (F and G) Time constants from the IIV protocol.