Theoretical and experimental studies on viscoelastic properties of erythrocyte membrane

Abstract

The deformation of a portion of erythrocyte during aspirational entry into a micropipette has been analyzed on the basis of a constant area deformation of an infinite plane membrane into a cylindrical tube. Consideration of the equilibrium of the membrane at the tip of the pipette has generated the relation between the aspirated length and the dimensionless time during deformational entry as well as during relaxation after the removal of aspiration pressure. Experimental studies on deformation and relaxation of normal human erythrocytes were performed with the use of micropipettes and a video dimension analyzer which allowed the continuous recording of the time-courses. The deformation consisted of an initial rapid phase with a membrane viscosity (range 0.6 x 10(-4) to 4 x 10(-4) dyn.s/cm) varying inversely with the degree of deformation and a later slow phase with a high membrane viscosity (mean 2.06 x 10(-2) dyn.s/cm) which was not correlated with the degree of deformation. The membrane viscosity of the recovery phase after 20 s of deformation (mean 5.44 x 10(-4) dyn.s/cm) was also independent of the degree of deformation. When determined after a short period of deformation (e.g., 2 s), however, membrane viscosity of the recovery phase became lower and agreed with that of the deformation phase. These results suggest that the rheological properties of the membrane can undergo dynamic changes depending on the extent and duration of deformation, reflecting molecular rearrangement in response to membrane strain.

Measurement Techniques for Red Blood Cell Deformability: Recent Advances

“…Shear modulus of lipid bilayers is essentially zero due to its fluidity nature; shear modulus of RBC is mainly contributed from the spectrin network. The shear moduli of RBC membranes have been extensively measured by micropipette aspiration; the values for µ are in the range of 6-10 µ N/m (Evans and La Celle,1975;Chien, Sung et al,1978;Waugh and Evans,1979;Evans, Mohandas et al,1984). Techniques based on optial tweezers (Lenormand, Hénon et al,2001;Dao, Lim et al,2003), magnetic twisting cytometry (Puig-de-Morales- Marinkovic, Turner et al, 2007), and dynamic membrane fluctuation measurements have also reported consistent values for µ.…”

“…where Rp is the radius of the micropipette, p is the applied pressure (Evans,1973;Chien, Sung et al,1978). Using micropipette aspiration, the value for µ was measured as 91.7 µN/m (Evans, Mohandas et al,1984).…”

A Model Incorporating Some of the Mechanical and Biochemical Factors Underlying Clot Formation and Dissolution in Flowing Blood

“…The shear-thinning nature of blood has been tied to the disaggregation of the RBC-rouleau aggregates that form at low shear and the deformability of the RBCs (Chien et al, 1967a,b), while its stress-relaxation properties are tied to the viscoelastic nature of the RBC membrane (Evans and Hochmuth, 1976;Chien et al, 1978). The viscoelastic behavior of blood is less prominent at higher shear rates (Thurston, 1973).…”

Micropipette Aspiration of Substrate-attached Cells to Estimate Cell Stiffness

“…In earlier studies, micropipette aspiration was performed either on liposomes 5 or on cells that were not attached to the substrate 2,[11][12][13] . In our studies, however, the cells are typically maintained attached to the substrate to avoid changes in the cytoskeletal structure that are likely to occur when cells detach [14][15][16] .…”