High frequency and low concentration - Limitation for impedance measurements

Abstract

The feasibility of impedance measurement as tool for detecting changes in plasma membranes is well accepted. Especially the changes due to electrical treatment of cells are easy detectable. It was postulated, that the impedance at higher frequency reveals the influence of electrical treatment on organelles like mitochondria. Using modelling and control experiments we could prove the impossibility for significantly detecting changes on membranes of intracellular compounds with the technique available today. If, for instance, the conductance of all mitochondria of Jurkat cells changes by an order of magnitude, the total impedance at 100 MHz changes by about 10-5 owing to the relatively small concentration of these organelles. Given the much bigger impedance changes of the plasma membrane, endoplasmatic reticulum and golgi apparatus, it becomes improbable to detect the changes of membranes of small organelles like mitochondria by impedance measurement. In a separate study we show the limits of organelle size and concentration for the recognition of changes due to high voltage treatment using impedance measurement between 16 kHz and 1 GHz. © Springer-Verlag 2007.