Multiscale Models and Measurements of Muscle Forces
Technical Report,01 Sep 2013,31 Aug 2014
University of Washington Seattle United States
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Muscle is active, regulated, soft matter that generates force complex interactions among millions of molecular motors organized in a highly structured compliant lattice of protein filaments. We pursued experimental tests to determine whether there are conditions under which key assumptions underlying models of force generation are violated e.g. no radial motion, uniform strain, no viscous dynamics. Our objectives were to 1 examine the interplay between changes in axial and radial dimensions of muscle and the controlled activation of crossbridges and 2 to determine if axial and radial strain non-uniformities arise in impulsive length changes applied to active muscle. Using workloop experiments on isolated muscle fibers in conjunction with high-speed laser and X-ray diffraction methods, we asked whether there is appreciable radial motion in the spacing of contractile filaments and whether crossbridges influence that motion. In addition, using rapidlength changes applied to active muscle we also ask if there are strain non-uniformities that propagate as traveling viscoelastic waves at the cellular level. These experiments will reveal whether a unexplored physical properties contribute to muscle force generation and b a new model of the physics and energetics of force generation in living systems is required.
- Anatomy and Physiology
- Nuclear Physics and Elementary Particle Physics