Figure 5.

Effect of cMyBP-C on length-dependent changes in the rates of XB detachment (k_rel) and XB recruitment (k_df). Isometrically-activated ventricular preparations were subjected to a sudden 2% stretch in their muscle length and the elicited force responses were used to estimate (A) k_rel and (B) k_df in WT and KO groups at SL's 2.1 and 1.9 μm as described in the methods section (Cheng et al., 2013; Gresham et al., 2014). Two-Way ANOVA revealed a significant interaction effect (P < 0.05) on k_rel and post-hoc tests showed that k_rel significantly accelerated by ~32% at short SL vs. long SL in WT group but such a trend was absent in KO group. k_rel significantly accelerated by ~34% in KO vs. WT group at long SL (A). Two-Way ANOVA revealed a significant interaction effect (P < 0.005) on k_df and post-hoc tests showed that k_df significantly accelerated by ~50% at short SL vs. long SL in WT group but such a trend was absent in KO group. In addition, k_df significantly accelerated by ~39% in KO vs. WT group at long SL (B). Determinations were made from 6 to 13 multicellular preparations and 3 to 4 hearts per each group. Values are reported as mean ± s.e.m. ^*P < 0.05; ^**P < 0.005.