Mechanoelectrical feedback regulates the arrhythmogenic activity of pulmonary veins.
BACKGROUND
Atrial fibrillation is commonly associated with dilated pulmonary veins. Stretch has been shown to have mechano-electrical effects.


OBJECTIVE
To investigate whether stretch can increase the arrhythmogenic activity of the pulmonary veins.


METHODS
The transmembrane action potentials were recorded from rabbit pulmonary veins before and after stretch (100 and 300 mg). Gadolinium and streptomycin (stretch-activated ion channel blockers) were each perfused into the pulmonary veins under a 300-mg stretch.


RESULTS
Stretch (0, 100 and 300 mg) force dependently increased the incidence of spontaneous activity (22%, 48% and 83%; p<0.05), mean (standard deviation (SD)) firing rates of spontaneous activity (1.7 (0.2), 2.1 (0.3) and 3 (0.2) Hz; p<0.05) and incidence of early post-depolarisations (9%, 26% and 61%; p<0.05) and delayed post-depolarisations (0%, 4% and 30%; p<0.05) in 23 pulmonary veins. In the seven preparations with spontaneous activity after the 300-mg stretch, gadolinium (1, 3 and 10 mumol/l) decreased the incidence of spontaneous activity by 43%, 29% and 14%, respectively (p<0.05), and decreased the firing rate from 2.9 (0.1) Hz to 0.8 (0.4), 0.3 (0.1) and 0.1 (0.1) Hz, respectively (p<0.05). Streptomycin (10 and 40 mumol/l) decreased the incidence of spontaneous activity by 71% and 29%, respectively (p<0.05), and decreased the firing rate from 2.9 (0.1) Hz to 1.6 (0.4) and 0.5 (0.3) Hz, respectively (p<0.05).


CONCLUSIONS
Stretch is an important factor in the electrical activity of the pulmonary vein. Stretch-induced arrhythmogenic activity of the pulmonary vein may contribute to the genesis of atrial fibrillation.
Chang
S-L
SL
Division of Cardiology and Cardiovascular Research Center, National Yang-Ming University School of Medicine and Veterans General Hospital, Taipei, Taiwan.
Chen
Y-C
YC
Chen
Y-J
YJ
Wangcharoen
W
W
Lee
S-H
SH
Lin
C-I
CI
Chen
S-A
SA
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D005246:Feedback; D005682:Gadolinium / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011667:Pulmonary Veins / Q000187:drug effects / Q000503:physiopathology*; D011817:Rabbits; D013307:Streptomycin / Q000494:pharmacology; D013314:Stress, Mechanical
D011500:Protein Synthesis Inhibitors; D005682:Gadolinium; D013307:Streptomycin