Evans E A, La Celle P L
Department of Biomedical Engineering, Duke University, Durham, N.C. 27706.
Blood. 1975 Jan;45(1):29-43.
Deformation of the erythrocyte membrane by the micropipette technique permits analysis of intrinsic material characteristics of the membrane and provides a means to differentiate purely membrane factors from such extrinsic factors as surface area-to-volume ratio. Using small micropipettes (less than 0.5 microns radius) to deform cells, it is evident that the red cell membrane behaves like a solid for periods of time up to 5-10 min of sustained deformation; for long periods of strain, permanent deformations occur, indicative of the semi-solid structural character. In the time range in which the membrane behaves like a solid, the material is linearly elastic up to strains of 400%, implying a loose network structure in the membrane plane, and evaluation of the elastic parameter mu (mu for normal discocytes equals 7 x 10(-3) dynes/cm) suggests that the elements comprising the network may have a molecular weight of approximately that of the water-soluble membrane protein spectrin. Whether the network system is cross-linked or simply a polymer solution remains unanswered. Experimental data indicate that plastic flow of the membrane under conditions of protracted strain may lead to permanent deformation of the membrane, whereas uniform dilation of the membrane, requiring over 1000 times more energy than for plastic flow, results in membrane failure and lysis. Analyses of the data from larger micropipettes of limiting mean cylindrical diameter show their utility in evaluating extrinsic factors, e.g., surface area-to-volume relationships, which are related to the capability of the whole cell to form a new configuration with implicit resistance to total surface area change, as the cell enters narrow channels of the microcirculation. Thus, micropipettes with diameters in the 2.7-3.0-microns range can provide sensitive comparisons of cellular deformability of erythrocytes.
通过微量移液器技术使红细胞膜变形，可分析膜的内在物质特性，并提供一种方法来区分纯膜因素与诸如表面积与体积比等外在因素。使用小口径微量移液器（半径小于0.5微米）使细胞变形，很明显红细胞膜在持续变形长达5 - 10分钟的时间段内表现得像固体；在长时间应变下，会出现永久性变形，这表明其具有半固体结构特征。在膜表现得像固体的时间范围内，材料在应变达到400%之前呈线性弹性，这意味着膜平面内存在松散的网络结构，对弹性参数μ（正常双凹圆盘状红细胞的μ等于7×10⁻³达因/厘米）的评估表明，构成网络的元素的分子量可能与水溶性膜蛋白血影蛋白的分子量大致相当。该网络系统是交联的还是仅仅是聚合物溶液仍未得到解答。实验数据表明，在长时间应变条件下膜的塑性流动可能导致膜的永久性变形，而膜的均匀扩张所需能量比塑性流动多1000倍以上，会导致膜破裂和裂解。对具有极限平均圆柱直径的较大微量移液器的数据进行分析，显示出它们在评估外在因素方面的效用，例如表面积与体积关系，当细胞进入微循环的狭窄通道时，这些关系与整个细胞形成具有隐含的总表面积变化抗性的新构型的能力相关。因此，直径在2.7 - 3.0微米范围内的微量移液器可以对红细胞的细胞变形性进行灵敏比较。
