Inorganic phosphate at millimolar concentrations accelerated relaxation in the absence of calcium and decreased steady active tension in the presence of calcium in skeletal muscle fibers.
Rapid laser pulse-induced photolysis of an adenosine triphosphate precursor in muscle fibers abruptly initiated cycling of the cross-bridges. The accompanying changes in tension and stiffness were related to elementary mechanochemical events of the energy-transducing mechanism. When inorganic phosphate was present at millimolar concentrations during liberation of adenosine triphosphate in the absence of calcium, relaxation was accelerated. Steady active tension in the presence of calcium was decreased but the approach to final tension was more rapid. These results suggest that, during energy transduction, formation of the dominant force-generating cross-bridge state is coupled to release of inorganic phosphate in a reaction that is readily reversible.
Hibberd et al. (Fri,) reported a other. Inorganic phosphate was evaluated on Tension and stiffness. Inorganic phosphate at millimolar concentrations accelerated relaxation in the absence of calcium and decreased steady active tension in the presence of calcium in skeletal muscle fibers.