Oxidative stress on pulmonary vein and left atrium arrhythmogenesis.
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.
Lin
Yung-Kuo
YK
Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan.
Lin
Feng-Zhi
FZ
Chen
Yao-Chang
YC
Cheng
Chen-Chuan
CC
Lin
Cheng-I
CI
Chen
Yi-Jen
YJ
Chen
Shih-Ann
SA
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
D000975:Antioxidants; D005609:Free Radicals; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid