Lee S H, Chen Y C, Chen S Y, Lin C I, Chen Y J, Chen S A
Shin Kong Wu Ho-su Memorial Hospital, Fu Jen Catholic University, Taiwan.
Eur J Clin Invest. 2008 Jan;38(1):17-23. doi: 10.1111/j.1365-2362.2007.01898.x.
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.
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.
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.
These findings suggest that the I(Cl,swell) plays an important role in the electrical activity of the PV cardiomyocytes.
肺静脉（PVs）含有对诱发心房颤动具有高致心律失常性的心肌细胞。肿胀激活外向整流Cl(-)电流（I(Cl,swell)）在心肌细胞电活动中起重要作用。本研究旨在探讨I(Cl,swell)是否在肺静脉电生理特性中发挥作用。
采用全细胞膜片钳技术，研究在等渗（290 - 300 mosm L(-1)）和低渗（220 - 230 mosm L(-1)）溶液中浸泡时，分离的兔单个肺静脉和心房心肌细胞的动作电位和I(Cl,swell)。使用共聚焦显微镜测量细胞长度和细胞宽度。
与无起搏活性的肺静脉心肌细胞或心房心肌细胞相比，低渗溶液在具有起搏活性的肺静脉心肌细胞中诱导出更大的I(Cl,swell)。低渗溶液使肺静脉心肌细胞的动作电位时程缩短，细胞宽度增加的程度大于心房心肌细胞。此外，低渗溶液通过减少瞬时内向电流和延迟后去极化来降低肺静脉发放冲动。
这些发现表明I(Cl,swell)在肺静脉心肌细胞电活动中起重要作用。
