Figure 3. Activation of the Ca²⁺ current is fast.

A, the rising phase of representative current traces for steps to −20 and −50 mV are shown. These were fitted with a 3rd order exponential (eqn (3):(dashed lines; τ = 476 μs at −50 mV and τ = 244 μs at −20 mV). To illustrate the faster rise at −20 mV, the peak value for I_Cafor the jump to −50 mV was scaled to the peak for −20 mV (dotted line). B, voltage dependence of τ. Voltages were corrected for junction potential and series resistance and linear interpolation was used to obtain values at the voltages indicated. These interpolated values were then averaged (n = 7–9).