FIGURE 7.
Differential modulation of Cav1.4 properties by α2δ1 and α2δ4. A and B, Ba2+ currents (IBa) were evoked by 50-ms depolarizations from a holding voltage of −80 mV in HEK293T cells transfected with Cav1.4 containing α2δ1 (n = 8) or α2δ4 (n = 9) and β2X13. A, representative IBa traces during a 50-ms depolarization to −70, 0, and +30 mV. B, current-voltage (I-V) plots for data obtained as in A. C, tail currents were evoked after 20-ms depolarization to various voltages from a holding voltage of −80 mV and repolarization to −60 mV. Tail currents were normalized to that obtained after a +80-mV pulse and plotted against test voltage. D, inactivation of IBa evoked by 5-s pulses from −80 to 0 mV. Left, representative traces. Right, inactivation was measured by dividing residual current amplitude (Ires) by the peak amplitude (Ipeak) in cells transfected with Cav1.4 containing α2δ1 (n = 5) or α2δ4 (n = 6), p = 0.59, by Student's t test. The time constant, τ, was obtained by fitting IBa decay with a single exponential function and was not different for α2δ1 and α2δ4; p = 0.88, Student's t test. Error bars, S.E.