Role of small-conductance calcium-activated potassium channels in atrial electrophysiology and fibrillation in the dog

Xiao Yan Qi, Jonas G. Diness, Bianca J.J.M. Brundel, Xiao Bo Zhou, Patrice Naud, Chia Tung Wu, Hai Huang, Masahide Harada, Mona Aflaki, Dobromir Dobrev, Morten Grunnet, Stanley Nattel

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BACKGROUND - : Recent evidence points to functional Ca-dependent K (SK) channels in the heart that may govern atrial fibrillation (AF) risk, but the underlying mechanisms are unclear. This study addressed the role of SK channels in atrial repolarization and AF persistence in a canine AF model. METHODS AND RESULTS - : Electrophysiological variables were assessed in dogs subjected to atrial remodeling by 7-day atrial tachypacing (AT-P), as well as controls. Ionic currents and single-channel properties were measured in isolated canine atrial cardiomyocytes by patch clamp. NS8593, a putative selective SK blocker, suppressed SK current with an IC50 of ≈5 μmol/L, without affecting Na, Ca, or other K currents. Whole-cell SK current sensitive to NS8593 was significantly larger in pulmonary vein (PV) versus left atrial (LA) cells, without a difference in SK single-channel open probability (Po), whereas AT-P enhanced both whole-cell SK currents and single-channel Po. SK-current block increased action potential duration in both PV and LA cells after AT-P; but only in PV cells in absence of AT-P. SK2 expression was more abundant at both mRNA and protein levels for PV versus LA in control dogs, in both control and AT-P; AT-P upregulated only SK1 at the protein level. Intravenous administration of NS8593 (5 mg/kg) significantly prolonged atrial refractoriness and reduced AF duration without affecting the Wenckebach cycle length, left ventricular refractoriness, or blood pressure. CONCLUSIONS - : SK currents play a role in canine atrial repolarization, are larger in PVs than LA, are enhanced by atrial-tachycardia remodeling, and appear to participate in promoting AF maintenance. These results are relevant to the potential mechanisms underlying the association between SK single-nucleotide polymorphisms and AF and suggest SK blockers as potentially interesting anti-AF drugs.

元の言語English
ページ(範囲)430-440
ページ数11
ジャーナルCirculation
129
発行部数4
DOI
出版物ステータスPublished - 28-01-2014
外部発表Yes

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All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

これを引用

Qi, X. Y., Diness, J. G., Brundel, B. J. J. M., Zhou, X. B., Naud, P., Wu, C. T., Huang, H., Harada, M., Aflaki, M., Dobrev, D., Grunnet, M., & Nattel, S. (2014). Role of small-conductance calcium-activated potassium channels in atrial electrophysiology and fibrillation in the dog. Circulation, 129(4), 430-440. https://doi.org/10.1161/CIRCULATIONAHA.113.003019