Figure 2.

Intrinsic and GTPγS-induced facilitation of Ca_v2.2b channels. (A) Prepulse facilitation of the rate of activation without GTPγS. A 10-ms test pulse (test 1) to +30 mV was applied from the holding potential of −80 mV. After 3 s, a 10-ms conditional prepulse to 100 mV was applied, the cell was repolarized to −80 mV for 1 ms, and a second 10-ms test pulse (test 2) identical to the first test pulse was applied. (Inset) Voltage clamp protocol. (B) Prepulse facilitation of the voltage dependence of activation without GTPγS. Tail currents were recorded following test 1 (●) and test 2 (○) at the indicated membrane potentials as described in A. Mean ± SEM of tail currents are plotted vs. test potential. (C) Prepulse facilitation of the rate of activation with 0.2 mM GTPγS, measured as in A. (D) Prepulse facilitation of the voltage dependence of activation with 0.2 mM GTPγS, measured as in B. (Scale bars: 0.1 nA, 4 ms.)