Irregularly appearing early afterdepolarizations in cardiac myocytes

Random fluctuations or dynamical chaos?

Daisuke Sato, Lai Hua Xie, Thao P. Nguyen, James N. Weiss, Zhilin Qu

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Irregularly occurring early afterdepolarizations (EADs) in cardiac myocytes are traditionally hypothesized to be caused by random ion channel fluctuations. In this study, we combined 1), patch-clamp experiments in which action potentials were recorded at different pacing cycle lengths from isolated rabbit ventricular myocytes under several experimental conditions inducing EADs, including oxidative stress with hydrogen peroxide, calcium overload with BayK8644, and ionic stress with hypokalemia; 2), computer simulations using a physiologically detailed rabbit ventricular action potential model, in which repolarization reserve was reduced to generateEADs and randomion channel or path cycle length fluctuationswere implemented; and 3), iterated mapswith or without noise.Bycomparing experimental,modeling, and bifurcation analyses,wepresent evidence thatnoise-induced transitions between bistable states (i.e., between an action potential with and without an EAD) is not sufficient to account for the large variation in action potential duration fluctuations observed in experimental studies. We conclude that the irregular dynamics of EADs is intrinsically chaotic, with random fluctuations playing a nonessential, auxiliary role potentiating the complex dynamics.

Original languageEnglish (US)
Pages (from-to)765-773
Number of pages9
JournalBiophysical Journal
Volume99
Issue number3
DOIs
StatePublished - Aug 4 2010
Externally publishedYes

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Cardiac Myocytes
Action Potentials
Rabbits
Hypokalemia
Ion Channels
Computer Simulation
Muscle Cells
Hydrogen Peroxide
Noise
Oxidative Stress
Calcium

ASJC Scopus subject areas

  • Biophysics

Cite this

Irregularly appearing early afterdepolarizations in cardiac myocytes : Random fluctuations or dynamical chaos? / Sato, Daisuke; Xie, Lai Hua; Nguyen, Thao P.; Weiss, James N.; Qu, Zhilin.

In: Biophysical Journal, Vol. 99, No. 3, 04.08.2010, p. 765-773.

Research output: Contribution to journalArticle

Sato, Daisuke ; Xie, Lai Hua ; Nguyen, Thao P. ; Weiss, James N. ; Qu, Zhilin. / Irregularly appearing early afterdepolarizations in cardiac myocytes : Random fluctuations or dynamical chaos?. In: Biophysical Journal. 2010 ; Vol. 99, No. 3. pp. 765-773.
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