Use of spin label and the flow-induced ESR spectral difference for studying erythrocyte deformation

Spin label study of erythrocyte deformability. Ca2+-induced loss of deformability and the effects of stomatocytogenic reagents on the deformability loss in human erythrocytes in shear flow

“…It is also known that with an increase in the intracellular Ca 2+ ion concentration, the cells suffer from a partial loss of the whole cell deformability (11,20,22,26,40,43). The erythrocyte deformability is assumed to be generally determined by the following factors: (a) physical properties of the membrane and cytoskeleton (e.g., elasticity); (b) the state of the cytoplasm (e.g., viscosity, hemoglobin concentration and aggregation); and (c) the geometry of the cell (e.g., shape, the surplus of the membrane surface area of the cell relative to its given volume) (14,19,23,32,35). Of the three factors, the second has been proposed in the past to be the principal mechanism of the Ca 2+-induced loss of deformability as the result of the cell dehydration and the consequent high internal viscosity (increase in hemoglobin concentration), because no loss of deformability was observed in a high potassium medium in which dehydration and K+ effilux are prevented (11,20).…”

“…To measure the deformability of red blood cells in laminar shear flow, we have utilized the electron paramagnetic resonance (EPR) spin label technique, combined with a computer-regulated variable flow device (23-25, 34, 35). It has been demonstrated experimentally and theoretically that the change in the EPR spectrum of a spin-labeled cell suspension observed in shear flow as compared with that at rest is closely related to the whole cell deformation and orientation (7-9, 23,34,35,37). The method provides a means to assess the degree of deformation and orientation as a function of volume flow rate in intact as well as variously treated cells.…”

Spin-label studies of erythrocyte deformability. IV. Relation of electron spin resonance spectral change with deformation and orientation of erythrocytes in shear flow

“…Recently, we have expanded the application of the electron spin resonance (ESR) spin-labeling method to assess the deformation of the red cells in shear flow by measuring the ESR spectral change induced by the flow, and also by observing the recovery process of the spectral difference when the flow is abruptly interrupted (2)(3)(4). In the previous papers of this series (2,4), we demonstrated that the change of the spectra by shear stress reflects the extent of both the whole cell deformation and orientation, which depend upon the intrinsic as well as the extrinsic mechanical properties of the cells.…”

Erythrocyte deformability of nonpregnant, pregnant, and fetal blood

“…In the present study, we used the ESR method which represents the actual deformation and orientation of an ensemble of cells as the ESR spectra, and assesses not only the cellular deformability but also the way red cells intereact with each other under a given set of fluid dynamic conditions [9,10,13,14]. Comparing to other methods, the main advantages of the ESR method are its greater sensitivity, its ability to measure the deformability at higher hematocrit value, and its greater sensitivity [14].…”

“…Erythrocyte deformability was measured by means of the ESR method, developed by NOJI et al; details of the method have been described elsewhere [5,6,13,14]. In brief, the ESR spectra were obtained using the ESR spectrometer (Model JEX-FEIXG, JEOL, Tokyo, Japan) with 100 kHz field modulation.…”