A new electro-optical approach for conductance measurement: an assay for the study of drugs acting on ligand-gated ion channels

A Menegon,C Poli,A Lanati,J F Rolland,R Rizzetto,L Redaelli,M Imberti,N Mazzocchi,F Grohovaz,S Pitassi

doi:10.1038/srep44843

A Menegon, C Poli + Show 8 more

Open Access

https://doi.org/10.1038/srep44843

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Abstract

Ligand gated ion channels are involved in many pathophysiological processes and represent a relevant, although challenging, target for drug discovery. We propose an innovative electro-optical approach to their analysis able to derive membrane conductance values from the local membrane potential changes imposed by test current pulses and measured by fast voltage-sensitive fluorescent dyes. We exploited the potential of this proprietary method by developing a drug testing system called “ionChannel Optical High-content Microscope” (ionChannelΩ). This automated platform was validated by testing the responses of reference drugs on cells expressing different ligand-gated ion channels. Furthermore, a double-blind comparison with FLIPR and automated patch-clamp was performed on molecules designed to act as antagonists of the P2RX7 receptor. ionChannelΩ proved highly reliable in all tests, resulting faster and more cost-effective than electrophysiological techniques. Overall, ionChannelΩ is amenable to the study of ligand gated ion channels that are receiving less attention due to limitations in current assays.

Highlights

Ligand gated ion channels are involved in many pathophysiological processes and represent a relevant, challenging, target for drug discovery
We investigated membrane potential variations in HeLa cells loaded with di-4-ANEPPS and exposed to symmetric biphasic electric pulses
An electro-optical approach that combines electrical field stimulation with detection of changes in membrane potential by voltage-sensitive dyes was proposed for the study of voltage-gated channels[9]

Summary

Introduction

Ligand gated ion channels are involved in many pathophysiological processes and represent a relevant, challenging, target for drug discovery. We exploited the potential of this proprietary method by developing a drug testing system called “ionChannel Optical High-content Microscope” (ionChannelΩ). This automated platform was validated by testing the responses of reference drugs on cells expressing different ligand-gated ion channels. IonChannelΩ is amenable to the study of ligand gated ion channels that are receiving less attention due to limitations in current assays. Higher time efficiency has recently been achieved by automated patch-clamp instrumentation, even though the HTS requirements for drug screening are not fully satisfied, for ligand-gated channels[4]. Slow-responding VSDs, widely used for their high www.nature.com/scientificreports/

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