Red Cell Rheology in Pulsative Flow

红细胞的流动特性影响循环血液的流变学特性。然而，对于动脉中脉动性剪切流动这一生理环境下红细胞的行为，我们所知甚少。因此，我们在实验室建立了脉动血流系统和流变仪，对脉动血流中的红细胞流变学进行了研究。(1)为了揭示红细胞变形对剪应力快速变化的响应，用流变仪观察了稀释悬浮液中红细胞变形的随时间变化过程。剪切应力呈正弦调制。在2Hz以上的调制频率下，在正弦波调制剪切应力的上相处检测到延迟响应。反应受(i)细胞内粘度，（ii）膜刚度和（iii）细胞内钙含量的影响。(2)利用计算机控制的脉动剪切流系统，研究了红细胞压积对脉动剪切流中红细胞变形的影响。(i)随着红细胞压积的增加，变形增强。（ii）红细胞变形随时间的变化表明，在高红细胞压积时，在脉动剪切应力下降阶段红细胞形状恢复到双凹形的速度减慢。(3)采用直径为250um的刚性管作为脉动流系统，研究了红细胞变形对脉动流压力-流动关系的影响。用压力传感器沿管道测量两点侧压力，测量两点间的压力传递效率。结果表明，影响压力传递效率的主要因素是悬浮液粘度，而不是红细胞变形性。

The flow properties of red cells affect the rheological characteristics of circulating blood. However, a little is known about red cell behavior under the pulsative shear flow which is physiological circumstance in arteries. Therefore, we studied the red cell rheology in pulsative flow with a rheoscope and a pulsative flow system built in our laboratory.(1) To reveal the response of red cell deformation to a rapid change in shear stress, the time-dependent process of red cell deformation in a diluted suspension was observed with a rheoscope. Shear stress was modulated sinusoidally. At a modulation frequency of above 2Hz, the retarded response was detected in the up-phase of the sinusoidally modulated shear stress. The response was affected by (i) intracellular viscosity, (ii) membrane stiffness, and (iii) intracellular calcium content.(2) The effect of hematocrit on red cell deformation in pulsative shear flow was studied with the pulsative shear flow system controlled by a computer. (i) The enhancement of deformation was detected with increasing hematocrit. (ii) The time dependent red cell deformation showed that shape recovery to biconcave shape in the down phase of pulsative shear stress was retarded at high hematocrit.(3) The effect of red cell deformation on the pressure-flow relationship of pulsative flow was studied with the pulsative flow system equipped with a rigid tube of 250 um in diameter. Lateral pressure was measured at two points along the tube with pressure transducers to measure the efficiency of pressure transmission between the two points. It was revealed that suspension viscosity, but not red cell deformability, affected the efficiency of the pressure transmission.