Fig. 11

Simulation of a quick change in the load during an isotonic afterloaded cycle in the TP + M model. The initial virtual sample length L_init is equal to 90%L_max. Dotted lines are for isometric contraction. Dashed lines show afterloaded contractions under different loads (20, 40 and 60% of peak isometric force F_isom at L_init). Solid lines show the traces for quick increase (a) and decrease (b) in the load approximately in the middle of the isotonic plateau. From top to bottom in both a and b: force, sample length, intracellular Ca²⁺ transient ([Ca²⁺]_i) and membrane potential changes. c, d The value tCa₇₀ is time from peak Ca²⁺ transient to 70% decay. APD₉₀ is action potential duration at 90% repolarization