[Spatial distribution of transverse stiffness of relaxed and activated rat soleus myofibers]

The transverse stiffness of isolated glycerinated and demembranized muscle fibers from soleus muscle of Wistar rat were measured in different functional states by atomic force microscopy. It was shown that transverse stiffness of relaxed fibers near the Z-disk projection is approximately twice as high as near the M-line. The transverse stiffness of demembranized fibers is much higher than that of glycerinated fibers for both the Z-disk and M-line. The activation of the fiber resulted in a significant increase in transverse stiffness. However, while the stiffness of activated glycerinated fibers near the Z-disk increased about twofold, demembranized fibers showed a more than fourfold increase in transverse stiffness compared to relaxed fibers. The stiffness of both glycerinated and demembranized fibers near the M-line increased approximately threefold.