Flag-RadΔCT cardiomyocytes display faster I _Ca,L decay kinetics. (A) Representative I_Ca,L current recorded for V_hold = −80 mV stepped to V_test = 0 mV, normalized to maximum peak current to highlight kinetic differences between Flag-Rad and Flag-RadΔCT. Black stars indicate the remaining current 30 ms after the peak current; black diamonds, 150 ms after the peak current. (B) Percent remaining current 30 ms after peak. Flag-RadΔCT had significantly less remaining current/faster decay (linear mixed model; genotype P = 0.002, F = 55.5362; voltage P = 0.058, genotype × voltage P = 0.002, F = 109.422). The remaining current was on average reduced 25% in Flag-RadΔCT (51% remaining current) relative to Flag-Rad (68%). (C) Percent remaining current 150 ms after peak across various test potentials. Flag-RadΔCT had significantly less remaining current/faster decay (linear mixed model; genotype P = 0.001, F = 80.672; voltage P < 0.001; interaction P < 0.001, F = 81.684). The remaining current was on average reduced 55% in Flag-RadΔCT (11% remaining current) relative to Flag-Rad (25%). For Flag Rad (N = 3 mice, n = 13 cells); for Flag-RadΔCT (N = 3 mice, n = 14 cells). Means of mice with SEM shown. Data points of individual cells and individual mice are in Fig. S3.