Open AccessCellular electrophysiology of canine pulmonary vein cardiomyocytes: action potential and ionic current properties
Author(s) -
Joachim R. Ehrlich,
Tae-Joon Cha,
L. Zhang,
Denis Chartier,
Peter Melnyk,
S. H. Hohnloser,
Stanley Nattel
Publication year - 2003
Publication title -
journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.046417
Subject(s) - repolarization , electrophysiology , cardiac transient outward potassium current , membrane potential , pulmonary vein , patch clamp , inward rectifier potassium ion channel , biophysics , voltage clamp , chemistry , ventricular action potential , resting potential , current clamp , medicine , cardiology , ion channel , atrial fibrillation , biology , receptor
Pulmonary vein (PV) cardiomyocytes play an important role in atrial fibrillation; however, little is known about their specific cellular electrophysiological properties. We applied standard microelectrode recording and whole-cell patch-clamp to evaluate action potentials and ionic currents in canine PVs and left atrium (LA) free wall. Resting membrane potential (RMP) averaged -66 +/- 1 mV in PVs and -74 +/- 1 mV in LA (P < 0.0001) and action potential amplitude averaged 76 +/- 2 mV in PVs vs. 95 +/- 2 mV in LA (P < 0.0001). PVs had smaller maximum phase 0 upstroke velocity (Vmax: 98 +/- 9 vs. 259 +/- 16 V s(-1), P < 0.0001) and action potential duration (APD): e.g. at 2 Hz, APD to 90% repolarization in PVs was 84 % of LA (P < 0.05). Na+ current density under voltage-clamp conditions was similar in PV and LA, suggesting that smaller Vmax in PVs was due to reduced RMP. Inward rectifier current density in the PV cardiomyocytes was approximately 58% that in the LA, potentially accounting for the less negative RMP in PVs. Slow and rapid delayed rectifier currents were greater in the PV (by approximately 60 and approximately 50 %, respectively), whereas transient outward K+ current and L-type Ca2+ current were significantly smaller (by approximately 25 and approximately 30%, respectively). Na(+)-Ca(2+)-exchange (NCX) current and T-type Ca2+ current were not significantly different. In conclusion, PV cardiomyocytes have a discrete distribution of transmembrane ion currents associated with specific action potential properties, with potential implications for understanding PV electrical activity in cardiac arrhythmias.