Figure 3. CDI reduction due to A760G mutation within the Ca_V1.3 long variant.

(A) Exemplar Ca²⁺ (red) and Ba²⁺ (black) current traces through the alternate splice variant Ca_V1.3_long illustrating decreased CDI as compared to the short splice variant (Fig. 1B). (B) Despite the reduction in magnitude, significant CDI is demonstrated by the difference in r₃₀₀ for Ca²⁺ (red) and Ba²⁺ (black), plotted across multiple voltages. (f₃₀₀ = 0.28 ± 0.04, n = 3). (C) Voltage activation curve for Ba²⁺ current through WT Ca_V1.3_long channels (V_1/2 = −1.0 ± 1.8 mV, n = 5). (D) Exemplar Ba²⁺ tail currents obtained from a transition from 80 mV to −40 mV (black) and −60 mV (green). Traces are normalized to one another such that the scale bars correspond to the traces of the same color. (E) Population data of the fast (top) and slow (bottom) deactivation time constants (τ) plotted as a function of voltage. Error bars indicate ± SEM, n = 5. (F) Exemplar current traces through A760G Ca_V1.3_long channels depicting diminished CDI as compared to WT channels. (G) Population data for r₃₀₀ (red = Ca²⁺, black = Ba²⁺) plotted across multiple voltages (f₃₀₀ = 0.10 ± 0.03; n = 4, *p < 0.05). (H) The activation curve of A760G Ca_V1.3_long channels (black, V_1/2 = −12.0 ± 2.1 mV, n = 4) shows an 11-mV hyperpolarizing shift (**p < 0.01) compared to WT (reproduced in gray for reference). (I) Exemplar Ba²⁺ tail currents for the A760G Ca_V1.3_long channel, obtained from a transition from 80 mV to −40 mV (black) and −60 mV (green). Traces are normalized to one another such that the scale bars correspond to the traces of the same color. (J) Population data of the fast (top) and slow (bottom) deactivation time constants (τ) plotted as a function of voltage for the A760G Ca_V1.3_long channel. Deactivation is significantly slowed as compared to WT reproduced as the gray dashed line (*p < 0.05, **p < 0.01). Error bars indicate ± SEM, n = 4.