title: Real-time imaging of electrical signals with an infrared FDA-approved dye.
abstract: Clinical methods used to assess the electrical activity of excitable cells are often limited by their poor spatial resolution or their invasiveness. One promising solution to this problem is to optically measure membrane potential using a voltage-sensitive dye, but thus far, none of these dyes have been available for human use. Here we report that indocyanine green (ICG), an infrared fluorescent dye with FDA approval as an intravenously administered contrast agent, is voltage-sensitive. The fluorescence of ICG can follow action potentials in artificial neurons and cultured rat neurons and cardiomyocytes. ICG also visualized electrical activity induced in living explants of rat brain. In humans, ICG labels excitable cells and is routinely visualized transdermally with high spatial resolution. As an infrared voltage-sensitive dye with a low toxicity profile that can be readily imaged in deep tissues, ICG may have significant utility for clinical and basic research applications previously intractable for potentiometric dyes.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois.
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Treger
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois; Committee on Neurobiology, University of Chicago, Chicago, Illinois.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Priest
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Raymond
authors.initials: R
authors.lastname: Iezzi
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois; Committee on Neurobiology, University of Chicago, Chicago, Illinois. Electronic address: fbezanilla@uchicago.edu.
authors.forename: Francisco
authors.initials: F
authors.lastname: Bezanilla
mesh_terms: D000200:Action Potentials; D000818:Animals; D017277:Drug Approval; D005456:Fluorescent Dyes / Q000378:metabolism*; D006801:Humans; D007208:Indocyanine Green / Q000378:metabolism*; D057054:Molecular Imaging / Q000379:methods*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051381:Rats; D014481:United States; D014486:United States Food and Drug Administration
chemical_list: D005456:Fluorescent Dyes; D007208:Indocyanine Green