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Cellular electrophysiology of canine pulmonary vein cardiomyocytes: action potential and ionic current properties
Author(s) -
Ehrlich Joachim R.,
Cha TaeJoon,
Zhang Liming,
Chartier Denis,
Melnyk Peter,
Hohnloser Stefan H.
Publication year - 2003
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2003.00801.x
Subject(s) - electrophysiology , current (fluid) , action (physics) , pulmonary vein , ionic bonding , chemistry , biophysics , medicine , cardiology , biology , ablation , physics , ion , organic chemistry , quantum mechanics , thermodynamics
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 ( V max : 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 V max in PVs was due to reduced RMP. Inward rectifier current density in the PV cardiomyocytes was ˜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 ˜60 and ˜50 %, respectively), whereas transient outward K + current and L‐type Ca 2+ current were significantly smaller (by ˜25 and ˜30 %, respectively). Na + ‐Ca 2+ ‐exchange (NCX) current and T‐type Ca 2+ 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.