Figure 2.

Closed-channel block of Ca_v1.2 channels by diltiazem (DTZ) at 0.03 Hz in Ca²⁺ and Ba²⁺. (A) DTZs (10, 50, 100, 500 and 1000 µM) were added to the bath solution containing 1.8 mM Ca²⁺ until equilibrium. Sample currents in the absence and presence of 100 µM DTZ are illustrated. (B) Dose–response curves of three Ca_v1.2 channels in 5 mM Ba²⁺. IC₅₀ was calculated from fits of individual dose–response curves to the Hill equation and summarized in (C). Δ indicates the exclusion of an exon. *P < 0.01, versus Ca_v1.2CM (one-way anova).