title: Oxidative stress on pulmonary vein and left atrium arrhythmogenesis.
abstract: BACKGROUND
  Oxidative stress and pulmonary veins (PVs) play critical roles in the pathophysiology of atrial fibrillation. The purpose of the present study was to investigate whether oxidative stress and antioxidant agents can change the electrophysiological characteristics of the left atrium (LA) and PVs.
  
  
  RESULTS
  Conventional microelectrodes were used to record the action potentials (APs) in isolated rabbit PV and LA specimens before and after H(2)O(2) administration with or without ascorbic acid or N-mercaptopropionyl-glycine (N-MPG, a free radical .OH scavenger). H(2)O(2) (0.02 and 0.2 mmol/L) decreased the PV spontaneous rates from 2.0+/-0.1 Hz to 1.6+/-0.1 Hz, and 1.7+/-0.1 Hz (n=10, P<0.05), but H(2)O(2) (2 mmol/L) increased PV spontaneous rates from 2.0+/-0.1 Hz to 2.8+/-0.2 Hz. H(2)O(2) easily induced PV burst firing and early afterdepolarizations, but not in the LA. H(2)O(2) shortened the AP duration and increased the contractile force to a greater extent in the LA than in PVs. In addition, the H(2)O(2)-induced PV burst firing and increasing spontaneous rates were suppressed or attenuated by pretreatment with ascorbic acid (1 mmol/L) or N-MPG (10 mmol/L).
  
  
  CONCLUSIONS
  H(2)O(2) significantly changed the electrophysiological characteristics of PV and LA through activation of free radicals and may facilitate the occurrence of atrial fibrillation.
authors.affiliation: Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yung-Kuo
authors.initials: YK
authors.lastname: Lin
authors.forename: Feng-Zhi
authors.initials: FZ
authors.lastname: Lin
authors.forename: Yao-Chang
authors.initials: YC
authors.lastname: Chen
authors.forename: Chen-Chuan
authors.initials: CC
authors.lastname: Cheng
authors.forename: Cheng-I
authors.initials: CI
authors.lastname: Lin
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
authors.forename: Shih-Ann
authors.initials: SA
authors.lastname: Chen
mesh_terms: D000200:Action Potentials; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid; D001281:Atrial Fibrillation / Q000209:etiology*; D022062:Electrophysiologic Techniques, Cardiac; D005609:Free Radicals; D006325:Heart Atria / Q000503:physiopathology*; D006861:Hydrogen Peroxide; D018384:Oxidative Stress; D011667:Pulmonary Veins / Q000378:metabolism*; D011817:Rabbits
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid