Bao J Z, Davis C C, Schmukler R E
Department of Electrical Engineering, University of Maryland, College Park 20742.
Biophys J. 1992 May;61(5):1427-34. doi: 10.1016/S0006-3495(92)81948-3.
We report measurements of the electrical impedance of human erythrocytes in the frequency range from 1 Hz to 10 MHz, and for temperatures from 4 to 40 degrees C. In order to achieve high sensitivity in this frequency range, we embedded the cells in the pores of a filter, which constrains the current to pass through the cells in the pores. Based on the geometry of the cells embedded in the filter a circuit model is proposed for the cell-filter saline system. A constant phase angle (CPA) element, i.e., an impedance of the form Z = A/(j omega)alpha, where A is a constant, j = square root of -1, omega is angular frequency, and 0 less than alpha less than 1 has been used to describe the ac response of the interface between the cell surface and the electrolyte solution, i.e., the electrical double layer. The CPA and other elements of the circuit model are determined by a complex nonlinear least squares (CNLS) fit, which simultaneously fits the real and imaginary parts of the experimental data to the circuit model. The specific membrane capacitance is determined to be 0.901 +/- 0.036 microF/cm2, and the specific cytoplasm conductivity to be 0.413 +/- 0.031 S/m at 26 degrees C. The temperature dependence of the cytoplasm conductivity, membrane capacitance, and CPA element has been obtained. The membrane capacitance increases markedly at approximately 37 degrees C, which suggests a phase transition in the cell membrane.
我们报告了在1赫兹至10兆赫兹频率范围内以及4至40摄氏度温度下对人体红细胞电阻抗的测量结果。为了在该频率范围内实现高灵敏度，我们将细胞嵌入过滤器的孔隙中，这使得电流只能通过孔隙中的细胞。基于嵌入过滤器中的细胞几何形状，提出了一个用于细胞 - 过滤器 - 盐水系统的电路模型。采用了一个恒定相位角（CPA）元件，即形式为Z = A/(jω)α的阻抗，其中A是一个常数，j = √(-1)，ω是角频率，且0 < α < 1，用于描述细胞表面与电解质溶液之间界面的交流响应，即双电层。电路模型的CPA和其他元件通过复非线性最小二乘法（CNLS）拟合来确定，该方法同时将实验数据的实部和虚部拟合到电路模型。在26摄氏度时，确定比膜电容为0.901±0.036微法/平方厘米，比细胞质电导率为0.413±0.031西门子/米。已经获得了细胞质电导率、膜电容和CPA元件的温度依赖性。膜电容在约37摄氏度时显著增加，这表明细胞膜发生了相变。
