Alpha- and beta-dispersion of fixed platelets: comparison with a structure-based theoretical approach

The electrorotation behavior of chemically-fixed human platelets has been investigated over a frequency range of 16 Hz–33 MHz; the conductivity of the suspending media was varied between 0.7 and 16.0 mS m−1. At conductivity levels above 3.1 mS m−1 fixed platelets show a pronounced co-field rotation below 1 kHz, whereas above this frequency the β-dispersion indicates significantly increased membrane conductivity. A rather broad Maxwell–Wagner peak was observed, suggesting a pronounced dispersion due to the inner structure of platelets. The observed electrorotational spectra were compared with a structure-based model for the β-dispersion combined with the theoretical approach for the α-dispersion by Grosse and Shilov (J. Phys. Chem., 100 (1996) 1771). In general our theoretical approach is in accordance with our experimental results. These results thus suggest the usefulness of electrorotation for non-invasive studies of intracellular structure.