Fig. 3.

Simulation of isometric contractions at different sample lengths in the TP + M model. The initial length of the sample was decreased from 95% to 80%L_max (see inset from dark to light grey lines). a The steady-state signals for isometric force (as compared to the force F₀ generated at 95%L_max initial length), sarcomere length, and membrane potential are shown for all lengths considered. b The steady-state signals for the concentration of calcium–troponin C complexes ([Ca–TnC]), intracellular Ca²⁺ concentration ([Ca²⁺]_i) and Na⁺–Ca²⁺ exchange current (i_NaCa) for 85% and 95%L_max initial lengths. Dashed line in the intracellular Ca²⁺ concentration panel is for the numerical experiment where mechano-electric feedbacks were eliminated from the model by imposing isometric conditions on the sarcomere (see text for details)