Korean Circ J.  2006 Feb;36(2):108-114. 10.4070/kcj.2006.36.2.108.

Effects of Oxygen Free Radical on Action Potential in Mouse Atrial Myocardium

Affiliations
  • 1Division of Cardiology, Chonnam University Hospital, Gwangju, Korea. chojg@unitel.co.kr
  • 2Pharmacology, Chonnam National University Medical School, Gwangju, Korea.
  • 3Chonnam National University Research Institute of Medical Sciences, Gwangju, Korea.

Abstract

BACKGROUND AND OBJECTIVES: Reactive oxygen species are known to be produced when atrial fibrillation develops. This study was performed to investigate the effects of hydrogen peroxide (H2O2) on the action potential parameters of the mouse atrium.
SUBJECTS AND METHODS
Mouse (ICR) atrial fibers were excised and immersed in cold bicarbonate-containing Tyrode's solution. The preparations were then perfused with oxygenated (95% O2, 5% CO2) Tyrode's solution and driven by an electrical stimuli 1 ms in duration at a frequency of 1 Hz. The transmembrane potentials were recorded at 0, 2.5, 5, 10, 20 and 30 minute, and compared between groups I (control), II (H2O2 0.1 mM), III (H2O2 0.5 mM) and IV (H2O2 1 mM).
RESULTS
In group I, the maximal diastolic potential (MDP), action potential amplitude (APA), maximal slope at phase 0 depolarization (Vmax), action potential duration until 50% and 90% of repolarization (APD50, APD90) were unchanged with increasing time. In group II, the MDP and APA were unchanged, but the Vmax was decreased, and the APD50 and APD90 prolonged. In group III, the MDP was increased and the Vmax decreased; the APD50 and APD90 were prolonged, but the APA unchanged. In group IV, the MDP was increased, the Vmax and APA decreased And the APD50 and APD90 prolonged. After-depolarization was observed in 40% (8/20) and 54.5% (12/22) of groups III and IV, respectively, and asystole occurred in 18.2% (4/22) of group IV.
CONCLUSION
Hydrogen peroxide changed the action potential parameters in both time and dose dependent manner, and also elicited after-depolarization at higher concentrations. These results suggest reactive oxygen species are involved in the electrical remodeling and arrhythmogenesis in atrial myocardium.

Keyword

Free radicals; Action potentials; Atrial fibrillation

MeSH Terms

Action Potentials*
Animals
Atrial Fibrillation
Atrial Remodeling
Free Radicals
Heart Arrest
Hydrogen Peroxide
Membrane Potentials
Mice*
Myocardium*
Oxygen*
Reactive Oxygen Species
Free Radicals
Hydrogen Peroxide
Oxygen
Reactive Oxygen Species
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