Deformation response of red blood cells in oscillatory shear flow.

The characteristics of red cell deformation were studied, focusing on deformation response of the cells subjected to oscillatory shear stress. Red blood cells were fractionated into subpopulations of different densities, i.e., low-density and high-density cells. The deformation response of the fractionated cells was evaluated with a rheoscope varying their intracellular viscosity and oscillation frequency of the applied shear stress, and determinants of the deformation response were compared with those of whole cell deformation under stationary shear stress. When the fractionated cells were exposed to sinusoidally oscillated shear stress, the cells underwent oscillatory deformation. The degree of deformation of the low-density cells correspond to the magnitude of the applied shear stress up to an oscillation frequency of 2.7 Hz. Meanwhile, such an oscillatory deformation as to correspond to the applied shear stress was observed up to 1.7 Hz for the high-density cells. It was suggested that intracellular viscosity was an important factor to determine the deformation response of red cells to oscillatory shear stress.