Dresden 2009 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 4: Cell Mechanics

BP 4.4: Vortrag

Montag, 23. März 2009, 15:15–15:30, HÜL 186

ATP dependent nonequilibrium mechanics of red blood cells — •Timo Betz, Martin Lenz, Jean-François Joanny, and Cécile Sykes — Institut Curie, UMR CNRS 168, 11 rue Pierre et Marie Curie, 75248 Paris, France

Red blood cells are extremely elastic objects, able to recover their shape even after large deformation as when passing through tight capillaries. The reason for this exceptional properties is found in the composition of the RBC membrane and its interaction with the spectrin cytoskeleton. We investigate the mechanics of the RBC membrane by a novel noninvasive technique that allows for the measurement of the fluctuation amplitudes with µs time and sub nm spatial resolution. This technique was used to determine the internal viscosity and the membrane bending modulus of normal red blood cells. We show that the mechanics do highly depend on the interaction between the membrane and the spectrin cytoskeleton which was altered by inhibition and activation of the 4.1 R proteins that connects the spectrin cytoskeleton with the membrane. Our results show that on short timescales (faster 100ms) the fluctuation are excited exclusively by thermal energy, whereas at timescales longer than 100ms an active energy that we contribute to the ATP consuming phosphorylation of the 4.1R protein can be measured. Hence at high frequencies, RBC membrane fluctuation can be described by thermodynamic equilibrium, whereas at longer timescales an active energy should be considered.