title: Optical electrophysiology for probing function and pharmacology of voltage-gated ion channels.
abstract: Voltage-gated ion channels mediate electrical dynamics in excitable tissues and are an important class of drug targets. Channels can gate in sub-millisecond timescales, show complex manifolds of conformational states, and often show state-dependent pharmacology. Mechanistic studies of ion channels typically involve sophisticated voltage-clamp protocols applied through manual or automated electrophysiology. Here, we develop all-optical electrophysiology techniques to study activity-dependent modulation of ion channels, in a format compatible with high-throughput screening. Using optical electrophysiology, we recapitulate many voltage-clamp protocols and apply to Nav1.7, a channel implicated in pain. Optical measurements reveal that a sustained depolarization strongly potentiates the inhibitory effect of PF-04856264, a Nav1.7-specific blocker. In a pilot screen, we stratify a library of 320 FDA-approved compounds by binding mechanism and kinetics, and find close concordance with patch clamp measurements. Optical electrophysiology provides a favorable tradeoff between throughput and information content for studies of NaV channels, and possibly other voltage-gated channels.
authors.affiliation: Departments of Chemistry and Chemical Biology and Physics, Harvard University, Cambridge, United States.|Howard Hughes Medical Institute, Harvard University, Cambridge, United States.
authors.forename: Hongkang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Departments of Chemistry and Chemical Biology and Physics, Harvard University, Cambridge, United States.
authors.forename: Elaine
authors.initials: E
authors.lastname: Reichert
authors.affiliation: Departments of Chemistry and Chemical Biology and Physics, Harvard University, Cambridge, United States.|Howard Hughes Medical Institute, Harvard University, Cambridge, United States.
authors.forename: Adam E
authors.identifier: 0000-0002-8699-2404
authors.initials: AE
authors.lastname: Cohen
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods*; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D062556:NAV1.7 Voltage-Gated Sodium Channel / Q000235:genetics / Q000378:metabolism*; D055096:Optical Devices; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D026941:Sodium Channel Blockers / Q000737:chemistry / Q000494:pharmacology*; D013050:Spectrometry, Fluorescence; D019076:Transgenes
chemical_list: C489457:KCNJ2 protein, human; D008164:Luminescent Proteins; D062556:NAV1.7 Voltage-Gated Sodium Channel; D024661:Potassium Channels, Inwardly Rectifying; C486866:SCN9A protein, human; D054852:Small Molecule Libraries; D026941:Sodium Channel Blockers; C413663:fluorescent protein 583; D049452:Green Fluorescent Proteins
keywords: biophysics; electrophysiology; high throughput screening; ion channels; neuroscience; none; optogenetics; structural biology