Figure 6.

Velocity-pCa data. (A) Native thin filament velocity (V_NTF) plotted as a function of free [Ca⁺⁺] in –log units (pCa). Thin filaments from Control tissue are plotted with filled black dots and solid line, IR2 thin filaments with gray diamonds and solid gray line and the filaments from IDNR are plotted with dark gray boxes and a dashed gray line. Points represent mean ± SEM and the data were fit with the Hill equation (see Methods). ^* Indicates significantly (p < 0.05) different from WT V_NTF. (B) Percentage of native thin filaments moving as a function of free [Ca⁺⁺] symbols and lines same as in (A). (C) Motility index, defined as the product of V_NTF and percent moving plotted as a function of free [Ca⁺⁺]. One animal myocardium was used for each condition. The data represent the average actin filament velocities from between 3 and 20 to 30 s videos at each pCa level and for each condition.