摘要
目的探讨家兔左心房后壁（LAPW）和左心耳底部组织（LAA）心肌细胞瞬时外向钾电流（Ito）及L-型钙电流（ICa-L）的特征以及哇巴因对其影响，提供LAPW和哇巴因在引起家兔左心房电不均一性和离子通道重构的电生理基础。方法使用离体心脏灌流系统灌注心脏，酶解法分离家兔LAPW和LAA心肌细胞。全细胞膜片钳技术记录两个部位心肌细胞Ito和ICa-L，观察哇巴因作用前后Ito和ICa-L．的变化，及其拟合后电流-电压（I—V）曲线改变。结果（1）根据记录1。电压钳制方案，当电位为＋50mV时，在正常对照组，LAPW心肌细胞Ito与LAA心房肌细胞Ito相比差异无统计学意义（P〉0．05）。但经哇巴因作用后，IAPW心肌细胞Ito的电流密度为（10．97±0．58）pA／pF（P〈0．01），LAA心房肌细胞Ito的电流密度为（9．39±0．83）pA／pF（与正常对照组和LAPW心肌细胞Ito相比，P〈0．05）。LAPW心肌细胞I。。的I-V曲线在原来最底部移到最上部。所有I—V曲线方向没有发生改变。（2）在记录ICa-L钳制方式下，正常对照组的LAPW心肌细胞ICa-L的最大电流密度明显小于LAA心房肌细胞ICa-L的最大电流密度（P〈0．05）。但经哇巴因作用后，LAPW心肌细胞ICa-L最大电流密度为（-11．13±0．99）pA／pF，IJAA心房肌细胞ICa．L为（-8．86±0．51）pA／pF（P〈0．01）。在正常对照组，LAPW心肌细胞ICa-L的I—V曲线位于最底部，经哇巴因作用后，LAPW心肌细胞ICa-L的I—V曲线上移到其他I．V曲线的最上部。每组ICa-L的I—V曲线整个形态没有发生明显变化，峰值的方向没有发生改变。结论LAPW心肌细胞存在离子流特异性差异，哇巴因加重LAPW心肌细胞Ito和ICa-L大小异质性和重新分配，这可能成为心房颤动易发性的启动因素和维持条件。
Objective To investigate the properties of electrophysiology and effects of ouabain upon transient outward potassium current （ Ito ） and L-type calcium current （ Ica_L ） of left atrium posterior wall （LAPW）and left atrium appendage tissue （LAA）in rabbit so as to provide the scientific explanations that LAPW and ouabain can enhance atrial fibrillation （AF） vulnerability through increasing electrophysiological heterogeneity and electrical remodeling of different regions of left atrium in rabbits. Methods Atrial myocytes from LAPWs and LAAs of rabbits on an in vitro heart perfusion system were obtained by enzymatic dissociation. The whole-cell patch-clamp technique was used to assess the effects of ouabain upon Ito and Ica_L. The current-voltage （I-V） curves of Ito and Ica.L in LAPW and LAA myocytes were fitted before and after ouabain administration. Results （ 1 ） With holding potential ± 50 mV and commanding potential ± 50 mV, the current densities of LAPW I,o decreased slightly less than that of LAA I,o in control groups （ P 〉 0. 05 ）. After ouabain administration, the current densities of LAPW Ito were significantly larger than that of LAA I,o [ （ 10. 97 ± 0.58） pA/pF vs （9. 39 ±- 0. 83 ） pA/pF, P 〈 0. 05 ]. The I-V curve of LAPW Ito was slightly lowered to I-V curve of LAA Ito in control groups. But with perfusion of ouabain, the I-V curve of LAPW I,o opposed to I-V curve of LAA ITo significantly changed from the bottom to the top with the same upward direction. （2） With the voltage clamp protocol of Ica_L, the current densities of LAPW Ica_L markedly decreased compared with that of LAA Ica.L in control groups （P 〈0. 05）. With the addition of ouabain, the peak of amplitude of LAPW Ic~_L at ±20 mV obviously increased to that of LAA ICa-L[ （ - 11. 13 ±0. 99）pA/ pF vs（ - 8.86 ±0. 51 ） pA/pF, P 〈0. 01 ]. In the control groups, the I-V curve of LAPW lca_L was shifted to the bottom of all I-V curves of ICa-L. Through the effects of ouabain, the I-
出处
《中华医学杂志》
CAS
CSCD
北大核心
2009年第44期3138-3142,共5页
National Medical Journal of China
基金
基金项目：国家自然科学基金（30700312）
关键词
心房颤动
心房
哇巴因
瞬时外向钾电流
L-型钙电流
Atrial fibrillation
Heart atria
Ouabain
Transient outward Potassium current
L-type calcium current
