Electrophysiological Ion Channel Screening using Lipid Bilayers

Abstract

Recently, the work of Tsofina et al. (Tsofina et al., Nature 212, 681 (1966)), in which lipid bilayers were formed from the mechanical union of lipid monolayers self-assembled on oil/water interfaces, has been extended in microfluidic devices (Funakoshi et al., Anal. Chem. 78, 8169 (2006) and droplet platforms (Holden et al., JACS. 129, 8650 (2007)), which have enabled simultaneous optical and electrical ion channel studies at the single channel level (Heron et al., JACS 131, 1652 (2009)). Our group has also shown that this method of bilayer assembly is also quite amenable to parallelism (Poulos et al., Biosens. Bioelectron. 24, 1806 (2009) and automation (Thapliyal et al., Biosens. Bioelectron. 26, 2651 (2010); Poulos et al., J. Phys. Condens. Matter 22, 454105 (2010)).In 2011 Leptihn et al. published single channel measurements of physiologically relevant ion channels in such bilayers (Leptihn et al., JACS 133, 9370 (2011)). I will present our work in which we have obtained ensemble measurements of the human cardiac potassium channel hERG (Kv11.1), rat TRPM8, and other physiologically relevant ion channels. I will also present our measurements of the conductance modulation of ion channel ensembles by known pharmaceutically active compounds at a range of concentrations, obtaining IC50 values that match the literature. I will report on our progress developing a parallel and automated platform to perform these measurements with increased throughput. Such a platform may find use in electrophysiological research to increase productivity of conventional lipid bilayer studies and enable screening of “hard to patch” ion channels.