Gaseous delivery of volatile anesthetics to a planar membrane

Volatile anesthetics are an important class of compounds that have become ubiquitous in healthcare. Current model systems used to explore the effects of these compounds in humans typically use tissue slices or cell culture. We are developing a simple protein-free assay to safely test the dose-dependent effects of volatile anesthetics on the fusion of liposomes to planar lipid bilayers. As an initial model, we use nitrogen gas bubbled through a concentrated ethanol solution to deliver ethanol vapor to an enclosed bilayer chamber, where the gaseous ethanol partitions into the chamber solution. Aqueous samples are taken over the span of the 40-minute experiment and measured by gas chromatography. Our data show that the flow rate of ethanol-saturated nitrogen gas and the stirring speed within the chamber heavily influence the rate of ethanol delivery. Initial experiments showed that the target concentration of 4% ethanol could be reached within 5 minutes of vapor delivery. As we have previously shown that ethanol alters fusion, delivery to the chamber will be further confirmed by measuring changes in membrane fusion. (Paxman, et al., 2017 Biophys J. 112:121-132). While our model currently has many limitations, our goal is to develop a fully contained assay that is safe to use with anesthetics such as diethyl ether and isoflurane, so as to further understand their effects on membrane fusion.