title: Molecular motions that shape the cardiac action potential: Insights from voltage clamp fluorometry.
abstract: Very recently, voltage-clamp fluorometry (VCF) protocols have been developed to observe the membrane proteins responsible for carrying the ventricular ionic currents that form the action potential (AP), including those carried by the cardiac Na(+) channel, NaV1.5, the L-type Ca(2+) channel, CaV1.2, the Na(+)/K(+) ATPase, and the rapid and slow components of the delayed rectifier, KV11.1 and KV7.1. This development is significant, because VCF enables simultaneous observation of ionic current kinetics with conformational changes occurring within specific channel domains. The ability gained from VCF, to connect nanoscale molecular movement to ion channel function has revealed how the voltage-sensing domains (VSDs) control ion flux through channel pores, mechanisms of post-translational regulation and the molecular pathology of inherited mutations. In the future, we expect that this data will be of great use for the creation of multi-scale computational AP models that explicitly represent ion channel conformations, connecting molecular, cell and tissue electrophysiology. Here, we review the VCF protocol, recent results, and discuss potential future developments, including potential use of these experimental findings to create novel computational models.
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
authors.forename: Wandi
authors.initials: W
authors.lastname: Zhu
authors.affiliation: MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, Debrecen, Hungary.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Varga
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA. Electronic address: jonsilva@wustl.edu.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Silva
mesh_terms: D000200:Action Potentials; D000818:Animals; D005470:Fluorometry / Q000379:methods*; D006321:Heart / Q000502:physiology*; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods*
chemical_list: D007473:Ion Channels
keywords: Action potential modeling; Calcium channels; Potassium channels; Sodium channels; Voltage clamp fluorometry