Determining the Composition of Active Cholesterol in the Plasma Membrane of Single Cells by using Electrochemiluminescence

Active and inactive cholesterol in the plasma membrane of one cell were co-measured by using luminol electrochemiluminescence, so that the composition of active membrane cholesterol was determined at single cells. The cellular plasma membrane remained intact after the removal of active membrane cholesterol and, thus, inactive cholesterol was activated for reaction with cholesterol oxidase. By utilizing the reactions of active and inactive cholesterol with oxidase in series, both of them generated hydrogen peroxide, inducing the corresponding electrochemiluminescence for the respective quantitation of these two states of membrane cholesterol. The successful determination of active and inactive membrane cholesterol at one cell provides information about the composition of active membrane cholesterol, which is significant for the study of cellular cholesterol trafficking.