Krueger M, Thom F
Medizinische Fakultät der Humboldt Universität, Charité, Institut für Transfusionmedizin, Berlin, Germany.
Biophys J. 1997 Nov;73(5):2653-66. doi: 10.1016/S0006-3495(97)78294-8.
High-frequency electric fields can be used to induce deformation of red blood cells. In the temperature domain T = 0 degrees to -15 degrees C (supercooled suspension) and for 25 degrees C this paper examines for human erythrocytes (discocytes, young cell population suspended in a low ionic strength solution with conductivity sigma(25 degrees) = 154 microS/cm) in a sinusoidal electric field (nu = 1 MHz, E0 = 0-18 kV/cm) the following properties and effects as a function of field strength and temperature: 1) viscoelastic response, 2) (shear) deformation (steady-state value obtained from the viscoelastic response time), 3) stability (by experimentally observed breakdown of cell polarization and hemolysis), 4) electrical membrane breakdown and field-induced hemolysis (theoretical calculations for ellipsoidal particles), and 5) mechanical hemolysis. The items 2-4 were also examined for the frequency nu = 100 kHz and for a nonionic solution of very low conductivity (sigma(25 degrees) = 10 microS/cm) to support our interpretations of the results for 1 MHz. Below 0 degrees C with decreasing temperature the viscoelastic response time tau(res)(T) for the cells to reach steady-state deformation values d(infinity,E) increases and the deformation d(infinity,E)(T) decreases strongly. Both effects are especially high for low field strengths. The longest response time of approximately 30 s was obtained for -15 degrees C and small deformations. For 1 MHz the cells can be highly elongated up to 2.3 times their initial diameter a0 for 25 degrees and 0 degrees C, 2.1a0 for -10 degrees C and still 1.95a0 for -15 degrees C. For T > or = 0 degrees C the deformation is limited by hemolysis of the cells, which sets in for E0(lysis)(25 degrees) approximately 8 kV/cm and E0(lysis)(0 degrees) approximately 14 kV/cm. These values are approximately three times higher than the corresponding calculated critical field strengths for electrically induced pore formation. Nevertheless, the observed depolarization and hemolysis of the cells is provoked by electrical membrane breakdown rather than by mechanical forces due to the high deformation. For the nonionic solution, where no electrical breakdown is expected in the whole range for E0, the cells can indeed be deformed to even higher values with a low hemolytic rate. Below 0 degrees C we observe no hemolysis at all, not even for the frequency 100 kHz, where the cells hemolyze at 25 degrees C for the much lower field strength E0(lysis) approximately 2.5 kV/cm. Obviously, pore formation and growth are weak for subzero temperatures.
高频电场可用于诱导红细胞变形。在温度范围T = 0摄氏度至 -15摄氏度（过冷悬浮液）以及25摄氏度的条件下，本文研究了人红细胞（双凹圆盘状细胞，悬浮于低离子强度溶液中的年轻细胞群体，其在25摄氏度时的电导率σ(25℃)= 154微西门子/厘米）在正弦电场（频率ν = 1兆赫兹，电场强度E0 = 0 - 18千伏/厘米）中作为电场强度和温度函数的以下特性和效应：1）粘弹性响应；2）（剪切）变形（从粘弹性响应时间获得的稳态值）；3）稳定性（通过实验观察到的细胞极化破坏和溶血）；4）电膜破坏和场致溶血（椭球形颗粒的理论计算）；5）机械溶血。还针对频率ν = 100千赫兹以及电导率非常低的非离子溶液（σ(25℃)= 10微西门子/厘米）对第2 - 4项进行了研究，以支持我们对1兆赫兹结果的解释。在0摄氏度以下，随着温度降低，细胞达到稳态变形值d(∞,E)的粘弹性响应时间τ(res)(T)增加，而变形d(∞,E)(T)强烈减小。这两种效应在低场强下尤为显著。在 -15摄氏度和小变形情况下获得了最长约30秒的响应时间。对于1兆赫兹，在25摄氏度和0摄氏度时细胞可高度伸长至其初始直径a0的2.3倍，在 -10摄氏度时为2.1a0，在 -15摄氏度时仍为1.95a0。对于T≥0摄氏度，变形受细胞溶血限制，溶血在电场强度E0(lysis)(25℃)约为8千伏/厘米和E0(lysis)(0℃)约为14千伏/厘米时开始。这些值比电诱导孔形成的相应计算临界场强大约高三倍。然而，观察到的细胞去极化和溶血是由电膜破坏引起的，而非高变形产生的机械力。对于非离子溶液，在整个E0范围内预计不会发生电击穿，细胞确实可以在低溶血率下变形至更高值。在0摄氏度以下，我们根本未观察到溶血，即使对于100千赫兹的频率也是如此，在25摄氏度时该频率下细胞在低得多的电场强度E0(lysis)约为2.5千伏/厘米时就会溶血。显然，在零下温度下孔的形成和生长较弱。
