Observation of cellular cholesterol efflux at microcavity electrodes.

Cholesterol oxidase modified platinum microcavity electrodes are used to measure cholesterol efflux from the plasma membrane surface of a single neuron in the buccal ganglion of Aplysia at room temperature. A background subtraction analog chronocoulometry method is used to measure hydrogen peroxide accumulation in the microcavity volume resulting from cellular cholesterol efflux and enzymatic oxidation. The data are consistent with the aqueous diffusion model for cellular cholesterol efflux where plasma membrane cholesterol undergoes exchange with solution phase cholesterol.