FIGURE 3.

Impact of human recombinant troponin exchange on myofilament function. Average fit parameters were obtained from force-[Ca²⁺] relationships indexing myofilament Ca²⁺ sensitivity (EC₅₀; A, left bars) and length-dependent activation of Ca²⁺ sensitivity (A; ΔEC₅₀; right bars), maximum force development (F_max; B, left bars); and length dependence of force development (ΔF_max; B, right bars), the Hill coefficient, an index of cooperativity (nHill; C, right bars). C, left bars, summarizes tension cost, the slope of the ATPase-force relationship, an index that is proportional to cross-bridge detachment rate. Experiments were performed at 25 °C. Data are presented as mean ± S.E. *, p < 0.05 versus WT (number of samples as in Fig. 2). Error bars reflect S.E.