Figure 7.

D1R constitutive activity increases the number of functional Ca_V2.2 channels at the plasma membrane. (A) Individual (gray) and averaged (black) traces of ON gating Ca_V2.2 currents (top panel) and averaged Q_ON from HEK293T cells cotransfected with Ca_V2.2, Ca_Vα₂δ₁, Ca_Vβ₃, and either D1R (+D1R white bar; n = 17), D1RS199A (+D1RS199A white bar; n = 10), or empty plasmid (−D1R white bar; n = 10), with (+D1R gray bar; n = 5) or without (−D1R gray bar; n = 10) D1R loop 2 (0.2 µg cDNA per well; bottom panel). Reversal potential (V_rev, ∼60 mV) was estimated individually for each cell. (B) Q_ON versus peak Ca_V2.2 tail current (I_tail at −60 mV) plot for HEK293T cells coexpressing Ca_V2.2, Ca_Vα₂δ₁, Ca_Vβ₃ with (+D1R black dots; n = 22, r² = 0.61) or without D1R (−D1R open dots; n = 22, r² = 0.31). Lineal regression slopes are not different between the groups (P = 0.187; F = 1.798). One-way ANOVA with Tukey’s post-test (only significant comparisons shown, A). Extra sum of squares F test (B). pF, picofaradays. Data were expressed as mean ± SEM, and dots represent individual data points.