Holding potential–dependent inactivation curves for CaV1.3b are unaffected by AA. (A and B) Time constants for inactivation were measured at each voltage for CTL (filled circle) or 10 µM AA (open circle) from a holding potential of −60 mV. Currents from β1b-, β3-, and β4-containing channels were best fit with two exponentials, τfast (A) and τslow (B). Currents from β2a-containing channels were best fit with one exponential, τslow (n = 5–7; *, P < 0.05). (C) Currents were normalized to maximal inward current during the 40-ms test pulse after a 2.2-s conditioning pulse and plotted against the conditioning pulse voltage. Curves were fit to the Boltzmann equation. Conditions are the same as A and B. (Inset in box) Current remaining at the end of the conditioning pulse for CaV1.3b, β2a currents (r2200; from Fig. 7, A and C) was divided by the peak inward current and plotted against the voltage of the conditioning pulse (filled circle, CTL; open circle, AA; n = 13; *, P < 0.05).
