Elasticity of the human red blood cell skeleton

Abstract

We have measured by optical tweezers micromanipulations the area expansion and the shear moduli of spectrin skeletons freshly extracted from human red blood cells, in different controlled salinity conditions. At medium osmolarity (150 mOsm/kg), we measure K_C=9.7±3.4 μN/m, μ_C=5.7±2.3 μN/m, K_C/μ_C=2.1±0.7. When decreasing the osmolarity, both K_C and μ_C decrease, while K_C/μ_C is nearly constant and equal to about 2. This result is consistent with the predictions made when modeling the spectrin skeleton by a two‐dimensional triangular lattice of springs. From the measured elastic moduli we estimate the persistence length of a spectrin filament: ξ∼2.5 nm at 150 mOsm/kg.