Figure 7. Simulation of mechanical and energetic parameters of the shortening muscle.

A, dependence on T/T₀ of the average motor working stroke (d, red line) and of the average sliding distance during a motor working cycle (L_W, blue line). B, fraction of attached motors versus T/T₀. C, force per myosin motor relative to the isometric value (F/F₀) versus T/T₀. D, dependence on shortening velocity of the rate of ATP hydrolysis per myosin head (left ordinate, s⁻¹) and of the rate of energy liberation calculated as detailed in the text (right ordinate, mW g⁻¹). E, symbols: observed ATPase rate in control (black symbols) and in 10 mm P_i (green symbols) versus shortening velocity (open circles, He et al. 1999; filled circles, Potma & Stienen, 1996; open triangles, Sun et al. 2001). E, lines: model simulation in control (black) and in 10 mm P_i (green). F, efficiency versus shortening velocity. G and H, g_app and f_app versus shortening velocity. I, dependence on shortening velocity of the ratio (R) of the ATPase rate per myosin motor in 10 mm P_i over the control. Where present, the dashed lines are the simulations using the model that does not include the possibility of the motors slipping to the second actin.