An alternative mechanochemical model of muscle contraction successfully predicted the steady force-velocity relation, ATPase activity peak, and Ca2+ force development.
ABSTRACT An alternative mechanochemical model of muscle contraction is proposed. The model combines interaction among four elements: chemical kinetics of the actomyosin ATPase pathway, C a 2+ binding kinetics, mechanical coupling during P i release, and working stroke motion to constitute simultaneous relations among mechanical and chemical variables. The model is derived from a different basis than the classical Huxley model. Force developed from strongly attached crossbridges is related to chemical component concentrations, chemical equilibrium and rate constants for the ATPase activity, and velocity of contraction. The chemical dynamics of the ATPase activity is also related to the velocity of contraction. A model for P i release during force generation and a model for chemical-mechanical coupling transition during a working stroke are also proposed and are the important keys of the mechanochemical linkage in energy transduction and muscle dynamics. The steady force-velocity relation is predicted by only one dimensionless parameter, and it provides an excellent fit to the Hill force-velocity equation. The model is able to simultaneously predict the peak in the ATPase activity as a function of velocity of contraction and supports the argument of multiple cycles of crossbridge attachment per one ATP molecule hydrolysis. Also the relation between the amount of C a 2+ and the force development can be predicted from this model.
Long et al. (Wed,) conducted a other in Muscle contraction. Mechanochemical model of muscle contraction vs. Classical Huxley model was evaluated on Steady force-velocity relation, ATPase activity, and Ca2+ force development. An alternative mechanochemical model of muscle contraction successfully predicted the steady force-velocity relation, ATPase activity peak, and Ca2+ force development.