Figure 2.

Inactivation kinetics of Ca_V1.2 channels modulated by Ca_Vβ subunits and their mixtures. (A) Voltage dependence of the inactivation rate (determined as the fraction of peak current inactivated after 150 ms of depolarization) of Ca_V1.2/α₂δ1 coexpressed with Ca_Vβ_1a subunit (up-pointing triangles, n = 6), Ca_Vβ_1aCa_Vβ_2b combination (2:1) (solid circles, n = 5), Ca_Vβ_1aCa_Vβ_2b combination (1:1) (solid diamonds, n = 5), and Ca_Vβ_2b subunit (down-pointing triangles, n = 6), respectively. (B) Normalized representative Ba²⁺ currents through Ca_V1.2 channels traces evoked by 160 ms depolarization to +10 mV. (C) Percent of the current inactivation at 0.1-, 0.5-, 1-, and 5 s during 5-s test pulses to +10 mV. (Open, light-shaded, medium-shaded, and solid bars) Ca_Vβ_1a subunit (n = 5), Ca_Vβ_1aCa_Vβ_2b combination (2:1) (n = 4), Ca_Vβ_1aCa_Vβ_2b combination (1:1) (n = 4), and Ca_Vβ_2b subunit (n = 6) experiments, respectively. ^∗p < 0.05; †p < 0.01, one-way ANOVA followed by Dunnett's post-test compared with Ca_V1.2 channels containing Ca_Vβ_2b subunits. The apparent differences between the two mixtures of Ca_Vβ_1aCa_Vβ_2b are not significant.