Figure 4. Analysis of verapamil, L-type Ca²⁺ channel blocker known to shorten QT duration.

(A) Representative traces of the contractile profile from the brightfield analysis show the QT shortening effect begin at 10 nM and the negative inotropic effect at 50 nM. (B) At 1 nM, the SVM accuracy was 64.52 ± 1.78%. At the 10, 50, and 100 nM concentrations, the SVM accuracies were all above 90%, strongly indicating verapamil’s cardio-modulating effect. (n = 14). (C) In the GCaMP6 method, significant changes were detected at the 50 and 100 nM concentrations (p ≤ 10⁻⁴ and p ≤ 10⁻⁴). (D) Looking at SR₉₀, significant differences were only detected at the 100 nM (p = 8.78 × 10⁻⁴) (n = 14). ***p ≤ 0.001.