Myosin Kinetics Influence Force Depression in Drosophila Jump Muscle

Abstract

Force Depression (FD), a history-dependent phenomenon observed in skeletal muscle, is characterized by a decrease in force production after active shortening compared to an isometric contraction at the corresponding final length. FD measured at steady-state (FDss) increases with larger shortening amplitudes, and decreases with increasing shortening rates. Furthermore, an increase in FDss is associated with a slower rate of force redevelopment following active shortening. Despite these experimental characterizations, the underlying mechanism(s) of FD remain unknown.