(A, B, and C) Show comparison of responses between mavacamten and para-nitroblebbistatin in BcSTF for SRX population (Aslow), DRX rate (kfast), and SRX rate (kslow), respectively, while (D, E, and F) show the respective comparisons in BcMF. (G, H, and I) Show a comparison of responses in BcSTF in the presence and absence of 10 μM blebbistatin for Aslow, kfast, and kslow, respectively. BcSTF refers to bovine cardiac synthetic thick filaments, and BcMF refers to bovine cardiac myofibrils. The data were presented on the absolute scale (% for amplitude and s−1 for rates). Concentrations of mavacamten required to attain half-maximal change (AC50/IC50) in parameters are listed in Table 1. Data are expressed as mean±SEM (n≥8 from two experiments that used single preparation of the same reagent purification).