PoC - Physics of Cancer - Annual Symposium
Poster, Friday, 19:00  
Hydrodynamic deformation reveals two coupled timescales/modes of red blood cell relaxation

S. Braunmüller1, Lothar Schmid1, Erich Sackmann2, Thomas Franke1,3
 
1
University Augsburg, EP1, Microfluidics Group, Universitaetsstraße 1, 86159 Augsburg, Germany
2
Technical University Munich, Physics Department, Biophysics and Molecular Materials, Amalienstraße 54,
80799 Munich, Germany
3
Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, 80539 Munich, Germany

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During their transport through the capillaries of blood vessels erythrocytes get repeatedly deformed many times. The elastic deformability of red cells in microcirculation is essential to maintain their shape and function for a life time of about 120 days. This enormous reversible shape deformability is based on the one hand on the non-spherical discoid biconcave resting shape and on the other hand on the mechanical properties of the lipid bilayer and the underlying cytoskeleton.
We have observed for the first time two modes of shape and rotational relaxation simultaneously in one single continuous experiment by analyzing the relaxation of parachute shaped red cells. This allows us to consecutively measure both timescales corresponding to one individual red cell and to correlate the relaxation times. We find a linear relationship between the timescales and observe that with increasing deformation-timescale also the timescale of rotational relaxation increase. We conclude that both timescales depend on the same parameter given by the network mechanics of the cytoskeleton. Upon metabolic depletion and extracellular addition of ATP we modify the extent of cytoskeletal defects in the spectrin network and relate it to the mechanical properties of the red blood cell.
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