Force Responses and Sarcomere Dynamics of Cardiac Myofibrils Induced by Rapid Changes in [P_i].

ABSTRACT: The second phase of the biphasic force decay upon release of phosphate from caged phosphate was previously interpreted as a signature of kinetics of the force-generating step in the cross-bridge cycle. To test this hypothesis without using caged compounds, force responses and individual sarcomere dynamics upon rapid increases or decreases in concentration of inorganic phosphate [P_i] were investigated in calcium-activated cardiac myofibrils. Rapid increases in [P_i] induced a biphasic force decay with an initial slow decline (phase 1) and a subsequent 3-5-fold faster major decay (phase 2). Phase 2 started with the distinct elongation of a single sarcomere, the so-called sarcomere "give". "Give" then propagated from sarcomere to sarcomere along the myofibril. Propagation

SUBMITTER: Stehle R 

PROVIDER: S-EPMC5266088 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature