Kinetic effects of cMyBP-C ablation in mECT. (A and B) Averaged amplitude-normalized first order derivative (dF/dt) traces. Solid blue lines show vehicle-treated WT mECT, solid red lines show vehicle-treated cMyBP-C^−/− mECT, dashed blue lines show dobutamine-treated WT mECT, and dashed red lines show dobutamine-treated cMyBP-C^−/− mECT. (C–E) Normalized maximum contractile velocity (+dF/dt_Max/F_Max; C), normalized maximum relaxation velocity (−dF/dt_Max/F_Max; D), and the dF/dt ratio (+dF/dt_Max/−dF/dt_Max; E). (F–H) The times to +dF/dt_Max (F), from dF/dt_Max to F_Max (G), and from F_Max to −dF/dt_Max (H). (C–H) Blue closed bars show vehicle-treated WT mECT, red closed bars show vehicle-treated cMyBP-C^−/− mECT, blue striped bars show dobutamine-treated WT mECT, and red striped bars show dobutamine-treated cMyBP-C^−/− mECT. *, P < 0.05 (one-way ANOVA with Tukey’s post hoc test; WT, n = 6; cMyBP-C^−/−, n = 7). (A–H) Error bars indicate SEM.