title: Arrhythmogenic transient dynamics in cardiac myocytes.
abstract: Cardiac action potential alternans and early afterdepolarizations (EADs) are linked to cardiac arrhythmias. Periodic action potentials (period 1) in healthy conditions bifurcate to other states such as period 2 or chaos when alternans or EADs occur in pathological conditions. The mechanisms of alternans and EADs have been extensively studied under steady-state conditions, but lethal arrhythmias often occur during the transition between steady states. Why arrhythmias tend to develop during the transition is unclear. We used low-dimensional mathematical models to analyze dynamical mechanisms of transient alternans and EADs. We show that depending on the route from one state to another, action potential alternans and EADs may occur during the transition between two periodic steady states. The route taken depends on the time course of external perturbations or intrinsic signaling, such as β-adrenergic stimulation, which regulate cardiac calcium and potassium currents with differential kinetics.
authors.affiliation: Departments of Pharmacology, University of California Davis, Davis, California.
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Departments of Pharmacology, University of California Davis, Davis, California.
authors.forename: Leighton T
authors.initials: LT
authors.lastname: Izu
authors.affiliation: Departments of Pharmacology, University of California Davis, Davis, California.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Bers
authors.affiliation: Departments of Pharmacology, University of California Davis, Davis, California. Electronic address: dsato@ucdavis.edu.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sato
mesh_terms: D000200:Action Potentials; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D008955:Models, Cardiovascular; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000502:physiology*
chemical_list: D007473:Ion Channels