Figure 6.

Fiber length (upper traces) and force (lower traces) changes when the amount of ATP utilized for mechanical response P_u was estimated at 0.25 s and 1 s after flash activation in the isometric condition (A) and in the practically unloaded condition (C_auxo = 48L₀/P₀) (B). In C, the values of P_u/P₀ in the isometric (solid circles) and the practically unloaded (open circles) conditions are plotted against time after flash activation. The records were obtained from the same preparation. Note that the difference in P_u between the two extreme conditions is much smaller at 0.25 s than at 1 s after flash activation.