Viscoelastic response of contractile filament bundles

Achim Besser, Julien Colombelli, Ernst H. K. Stelzer, Ulrich S. Schwarz

Phys. Rev. E, 83(5):051902, May 2011

The actin cytoskeleton of adherent tissue cells often condenses into
filament bundles contracted by myosin motors, so-called stress fibers,
which play a crucial role in the mechanical interaction of cells with
their environment. Stress fibers are usually attached to their
environment at the endpoints, but possibly also along their whole
length. We introduce a theoretical model for such contractile filament
bundles which combines passive viscoelasticity with active
contractility. The model equations are solved analytically for two
different types of boundary conditions. A free boundary corresponds to
stress fiber contraction dynamics after laser surgery and results in
good agreement with experimental data. Imposing cyclic varying
boundary forces allows us to calculate the complex modulus of a single
stress fiber.