Abstract
Automated patch-clamp (APC) systems have become indispensable tools of drug-discovery programs by allowing high-throughput electrophysiology-based screening of ion channel compounds. The recent development and introduction of microfluidics-based APC systems have made it possible to study the interactions of ligand-gated ion channels with pharmacological reagents, such as agonists, antagonists, or positive allosteric modulators (PAMs), with reliable pharmacological results comparable to those of the gold-standard manual patch-clamp technique while maintaining high-throughput capacity. Many ligand-gated ion channels exhibit rapid desensitization upon repetitive introduction of ligands; this loss of channel activity in the absence of pharmacological interaction poses a challenge for developing accurate, precise, and robust assays with high success rate, low run-down, and reliable pharmacological results. Here we present procedures to study nicotinic acetylcholine receptors (nAChRs) with the IonFlux™, an automated patch-clamp system with continuous flow and precise fluidic exchange; these procedures can also be generalized to the study of other ligand-gated ion channels. We present protocols to study agonist, antagonist, and PAM activities on nAChRs, particularly the rapidly desensitizing nAChR α7 receptors. The data demonstrate that the IonFlux™ system is a fast, robust, and reliable platform for the study of nAChRs and other ligand-gated ion channels, generating data that closely mimic those from manual patch-clamp conditions. © 2020 by John Wiley & Sons, Inc. Basic Protocol 1: Measuring agonist concentration-dependent response Basic Protocol 2: Measuring antagonist concentration-dependent response Basic Protocol 3: Measuring positive allosteric modulator (PAM) concentration-dependent response Support Protocol 1: Basic IonFlux system operation Support Protocol 2: Plate care and filling Support Protocol 3: Plate preparation for water rinsing Support Protocol 4: Water rinsing of plates Support Protocol 5: Plate priming Support Protocol 6: General assay Support Protocol 7: Editing the compound addition sequence (compound list) Support Protocol 8: Creating compound list for agonist concentration-dependent response Support Protocol 9: Creating compound list for antagonist or PAM concentration-dependent response Support Protocol 10: Defining the different compounds used or compound list Support Protocol 11: Maintenance Support Protocol 12: Data analysis Support Protocol 13: Cell culture.