DYNAMIC DEFORMATION AND RECOVERY RESPONSE OF RED BLOOD
CELLS TO A CYCLICALLY REVERSING SHEAR FLOW:
Effects of Frequency of Cyclically Reversing Shear Flow
and Shear Stress Level
Nobuo Watanabe 1, Hiroyuki Kataoka 2, Toshitaka Yasuda 2 and Setsuo Takatani 2*
1 Institute of Biomaterials and Bioengineering,Tokyo Medical and Dental University
2 Tokyo Medical and Dental University
* To whom correspondence should be addressed. E-mail: takatani.ao{at}tmd.ac.jp.
Submitted on January 26, 2005
Revised on February 23, 2005
Accepted on 1 June 2006
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Abstract |
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Dynamic deformation and recovery responses of red blood cells (RBCs) to a cyclically reversing shear flow generated in a 30 mu clearance, with the peak shear stress of 53, 108, 161, and 274 Pa at the frequency of 1, 2, 3, and 5 Hz, respectively, were studied. The RBCs' time varying velocity varied following the glass plate velocity without any time lag, while the L/W change, where L and W were the major and minor axes of RBCs' ellipsoidal shape, exhibited a rapid increase and gradual decay during deformation and recovery phase. The time of minimum L/W occurrence lagged behind the zero-velocity time of glass plate (zero stress), and the delay time normalized to the one cycle duration remained constant at 8.0%. The elongation of RBCs at zero stress time became larger with the reversing frequency. A simple mechanical model consisting of an elastic linear element during rapid elongation period and parallel combination of elements such as a spring and dashpot during non-linear recovery phase was suggested. The dynamic response behavior of RBCs under a cyclically reversing shear flow was different from the conventional shape change where a step-like force was applied to and completely released from the RBCs.
Key Words:
Cyclically reversing shear flow, Dynamic shear-deformation, Oscillatory couette flow,, Red blood cells, Shape recovery
