Effects of Cholesterol Depletion on Membrane Capacitance Cytoplasmic Conductivity

Cholesterol is a key molecule in a wide variety of cellular functions and serves as an important indicator for cellular properties. Cholesterol can be measured directly using fluorescent techniques or indirectly through biophysical properties, such as capacitance. To explore the relationship between membrane cholesterol depletion and electrical properties, single cell impedance spectroscopy was used. HEp2 cells were exposed to methyl-β-cyclodextrin, a cholesterol-depleting molecule, for varying treatment times. The level of depletion was determined using a Filipin-III fluorescent assay. A frequency sweep was performed in a microfluidic constriction channel, allowing the electrical properties to be extracted by fitting the data to a circuit model. Depletion of cholesterol was shown to affect both the membrane capacitance and the cytoplasmic conductivity. The capacitance decrease is thought to be caused by a decrease in surface area and the conductivity by changes in the ion concentration of the cytoplasm.M.A.S