Swelling activated chloride currents in the electrical activity of pulmonary vein cardiomyocytes.
BACKGROUND
Pulmonary veins (PVs) contain cardiomyocytes with a high arrhythmogenicity for inducing atrial fibrillation. The swelling-activated outwardly rectifying Cl(-) currents (I(Cl,swell)) are important in the electrical activity of cardiomyocytes. This study was to investigate whether I(Cl,swell) play a role in the PV electrophysiological characteristics.


METHODS
A whole-cell patch clamp was used to investigate the action potentials and I(Cl,swell) in isolated rabbit single PV and atrial cardiomyocytes during immersion in isotonic (290-300 mosm L(-1)) and hypotonic (220-230 mosm L(-1)) solutions. The cell length and cell width were measured using confocal microscopy.


RESULTS
Hypotonic solution induced larger I(Cl,swell) in the PV cardiomyocytes with pacemaker activity than those in the PV cardiomyocytes without pacemaker activity or atrial cardiomyocytes. Hypotonic solution shortened the action potential duration and increased the cell width to a greater extent in the PV cardiomyocytes than in the atrial cardiomyocytes. Moreover, hypotonic solution decreased the PV firing with a decrease in the transient inward currents and delayed after depolarizations.


CONCLUSIONS
These findings suggest that the I(Cl,swell) plays an important role in the electrical activity of the PV cardiomyocytes.
Lee
S H
SH
Shin Kong Wu Ho-su Memorial Hospital, Fu Jen Catholic University, Taiwan.
Chen
Y C
YC
Chen
S Y
SY
Lin
C I
CI
Chen
Y J
YJ
Chen
S A
SA
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001281:Atrial Fibrillation / Q000378:metabolism* / Q000473:pathology; D018118:Chloride Channels / Q000378:metabolism; D018613:Microscopy, Confocal; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology*; D018408:Patch-Clamp Techniques; D011667:Pulmonary Veins / Q000378:metabolism / Q000473:pathology*; D011817:Rabbits; D016896:Treatment Outcome
D018118:Chloride Channels