Key result
The actomyosin filament lattice in skeletal myofibrils is radially deformable, stabilized primarily by myosin head interactions under mild compression and electrostatic repulsive forces under severe compression.
Atomic force microscopy reveals that the actomyosin filament lattice in skeletal myofibrils is radially deformable and stabilized by myosin head interactions under mild compression and electrostatic repulsion under severe compression.
No immediate clinical implications; leaves open whether lattice mechanics translate to cardiac muscle or human disease.
The radial stability of the actomyosin filament lattice in skeletal myofibrils was examined by using atomic force microscopy. The diameter and the radial stiffness of the A-band region were examined based on force-distance curves obtained for single myofibrils adsorbed onto cover slips and compressed with the tip of a cantilever and with the Dextran treatment. The results obtained indicated that the A-band is composed of a couple of stiffness components having a rigid core-like component. It was further clarified that these radial components changed the thickness as well as the stiffness depending on the physiological condition of myofibrils. Notably, by decreasing the ionic strength, the diameter of the A-band region became greatly shrunken, but the rigid core-like component thickened, indicating that the electrostatic force distinctly affects the radial structure of actomyosin filament components. The results obtained were analyzed based on the elementary structures of the filament lattice composed of cross-bridges, thin filaments and thick filament backbones. It was clarified that the actomyosin filament lattice is radially deformable greatly and that (1), under mild compression, the filament lattice is stabilized primarily by the interactions of myosin heads with thin filaments and thick filament backbones, and (2), under severe compression, the electrostatic repulsive interactions between thin filaments and thick filament backbones became predominant.
No takes yet. Share an insight, caveat, or question.
Miyashiro et al. (2013) studied None (healthy rabbit skeletal muscle). Radial compression via atomic force microscopy and Dextran treatment vs. Uncompressed state / varying physiological states (rigor, relaxed, contracting) was evaluated on Diameter and radial stiffness of the A-band region. The actomyosin filament lattice in skeletal myofibrils is radially deformable, stabilized primarily by myosin head interactions under mild compression and electrostatic repulsive forces under severe compression.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: