Dielectric inspection of erythrocytes

We review our recent dielectric spectroscopy (DS) studies of rabbit erythrocytes of various shapes (spherocytes, echinocytes, enlarged erythrocytes, and discocytes) and present additional results obtained through a new analysis of the previous data. First, a numerical method to accurately obtain the specific cell membrane capacitance Cm and the cytoplasm conductivity κcp for non-spherical and non-ellipsoidal cells is demonstrated. This method uses numerical electromagnetic simulation with three-dimensional cellular modeling. The value of Cm for the discocyte agrees well with the reported values for swollen erythrocytes. In contrast to the numerical method, the analytical method, in which the discocyte must be assumed to have a spheroidal shape, rather than a more realistic biconcave shape, leads to significant overestimation of Cm. Second, DS is applied to monitor the dielectric response of preserved rabbit blood over 37 days. Microscope observation revealed that ∼90% of the erythrocytes were echinocytes at the beginning of preservation and that the erythrocytes started to transform into microspherocytes around the 20th day. The dielectric response also changed at the same critical point of the 20th day. Therefore, DS is revealed to be a sensitive tool for monitoring the deterioration of preserved blood.