Fundamental laws of the deformational behavior of erythrocytes in shear flow

Abstract

The dependences of the deformability parameter of erythrocytes on the shear stress in the Couette flow upon a change in their membrane rigidity or internal-content viscosity have been investigated by the diffractometric (ectacytometric) method. The results obtained suggest that the yield stress of cells measured by this method reflects the deformability of erythrocyte membranes, and the slope of the deformation curve rectified in the semilogarithmic coordinate system depends on the viscosity of the internal content of the cell. A parameter such as the limit deformation of erythrocytes is primarily determined by the viscosity of the membrane cytoskeleton.Introduction. There are several methods for investigating the deformational behavior of erythrocytes: membrane drawing in a pipette and filtration of erythrocytes through microfilters, especially with the use of nucleopores with d = 5 µm (for human erythrocytes) [1-3]. Again, the centrifugation method is worth mentioning [4]. At present, the better-substantiated diffractometric method is successfully competing with them [5,6]. This method relies on laserbeam diffraction by an erythrocyte suspension in the shear flow. Erythrocytes extended in the flow can be approximated with a good degree of accuracy by ellipsoids. A measure of erythrocyte deformation in the flow as a function of the shear stress is the deformability index defined by the relation DI = (L − H)/(L + H). With the aid of this method, Morris and Williams [7] investigated the hemolysis of erythrocytes in the presence of a shear stress and associated its value with the degree of "membrane fatigue." Phillips [8] proposed a physical substantiation of the method and showed that an increase in the ellipsoid length in the shear flow for normal erythrocytes occurs in accordance with the dependence ∆L ⁄ L = 0.19 ln (τ ⁄ τ 0 ), τ 0 = 0.38 N/m 2 .Results are independent of the erythrocyte size [9], which was used to reveal the features of the deformability of erythrocytes of various mammals. In particular, it was shown that ellipsoid-like erythrocytes (e.g., in the llama) do not deform and are only oriented in the flow. In [10], a dramatic decrease in the erythrocyte deformability upon the formation of Heinz bodies in them was revealed. The investigation of the effect of oxidative stress on the erythrocyte deformability showed that the greatest damage is caused by hydrogen peroxide [11], which was confirmed later in [12].In the rheology of erythrocytes, the problem of determining their "internal viscosity," introduced by Dintenfass as a deformability criterion [13], is still to be solved. While the methods for calculating the "internal viscosity" by means of viscosimetry were substantiated and recognized [14], it is still not known what contribution to this parameter is made by a change in the membrane properties and by a change in the internal content of the erythrocyte around which the membrane rotates in the shear flow [15].The aim of the present work is to find out to what extent the dependence of the deforma...

Hemorheological properties in patients with type-1 and type-2 diabetes mellitus

“…The maximal elongation of the cells was characterized by IDmax, determined at the maximal ! γ 2700 s-1 [16].…”

Study by optical techniques of the dependence of aggregation parameters of human red blood cells on their deformability

“…Usually they elongate in the direction of the flow, but also, they can change their shape dramatically in the vessels that are smaller than the size of the RBCs, for example, capillaries with a 3 to 5 µm radius [2]. A considerable contribution to the deformability comes from the elasticity of the cell membrane, as well as from the hemoglobin solution inside [3]. RBC deformability plays a significant role in the blood circulation.…”

Mechanosensitivity of cell membrane may govern creep-strain recovery, osmotic expansion and lysis.

“…During the last four decades many experiments of different type have been conducted to investigate the mechanical properties of the cell (Ananthakrishnan et al, 2006), and especially of the cell membrane, including: micropipette manipulation (Rand, 1964;Chien et al, 1978;Evans, 1983;Engström & Meiselman, 1998;Hochmuth, 2000;Shao & Xu, 2002;Ruef et al, 2004), cell poking (Daily et al, 1984;Duszyk et al, 1989;Goldmann, 2000), shear flow and fluid mechanical technique (Hochmuth et al, 1973;Pfafferott et al, 1985;Kon et al, 1987;Le et al, 1993;Firsov et al, 2006), osmotic expansion and lysis (Evans et al, 1976;Wolfe & Steponkus, 1983;Wolfe et al, 1986;Dowgert et al, 1987), electric field elongation (Engelhardt & Sackmann, 1988;Poznanski et al, 1992;Wanichapichart et al, 2002), magnetic bead microrheometry (Bausch et al, 1998;Wang et al, 2008), dynamic light scattering microscopy (Amin et al, 2007), optical tweezers (Hénon et al, 1999;Dao et al, 2003;Lian et al, 2004;), optical stretcher (Guck et al, 2000;, microplate manipulation (Thoumine et al, 1999;Desprat et al, 2005), and microhand and atomic force microscopy (Yamashina & Katsumata, 2000;Nishi et al, 2005). Some authors have proposed thermodynamics…”