title: Cardiac strength-interval curves calculated using a bidomain tissue with a parsimonious ionic current.
abstract: The strength-interval curve plays a major role in understanding how cardiac tissue responds to an electrical stimulus. This complex behavior has been studied previously using the bidomain formulation incorporating the Beeler-Reuter and Luo-Rudy dynamic ionic current models. The complexity of these models renders the interpretation and extrapolation of simulation results problematic. Here we utilize a recently developed parsimonious ionic current model with only two currents-a sodium current that activates rapidly upon depolarization INa and a time-independent inwardly rectifying repolarization current IK-which reproduces many experimentally measured action potential waveforms. Bidomain tissue simulations with this ionic current model reproduce the distinctive dip in the anodal (but not cathodal) strength-interval curve. Studying model variants elucidates the necessary and sufficient physiological conditions to predict the polarity dependent dip: a voltage and time dependent INa, a nonlinear rectifying repolarization current, and bidomain tissue with unequal anisotropy ratios.
authors.affiliation: Department of Physics, Oakland University, Rochester, Michigan, United States of America.
authors.forename: Suran K
authors.identifier: http://orcid.org/0000-0001-5268-1838
authors.initials: SK
authors.lastname: Galappaththige
authors.affiliation: Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland, United States of America.
authors.forename: Richard A
authors.identifier: http://orcid.org/0000-0003-2798-6378
authors.initials: RA
authors.lastname: Gray
authors.affiliation: Department of Physics, Oakland University, Rochester, Michigan, United States of America.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Roth
mesh_terms: D000200:Action Potentials / Q000502:physiology; D016880:Anisotropy; D004558:Electric Stimulation; D006321:Heart / Q000502:physiology*; D017136:Ion Transport; D008564:Membrane Potentials / Q000502:physiology; D008955:Models, Cardiovascular; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism; D016276:Ventricular Function
chemical_list: D024661:Potassium Channels, Inwardly Rectifying; D015222:Sodium Channels