摘要
目的探讨正常大鼠冠状动脉平滑肌细胞大电导钙离子激活钾通道（BK通道）电流的特点，为研究疾病状况下冠状动脉平滑肌细胞BK通道电流异常变化提供正常对照。方法酶消化法分离大鼠冠状动脉平滑肌细胞；采用不同阻滞剂，对冠状动脉血管平滑肌细胞上钾通道进行鉴定；采用全细胞和单通道膜片钳实验技术分别记录冠状动脉平滑肌细胞BK通道电流，计算开放幅度和电导，观察BK通道电压敏感性和钙敏感性及加入特异性BK通道阻滞剂IBTX后BK通道电流的变化。结果正常冠状动脉平滑肌细胞BK通道电流约占总钾离子流65％±4％（t／,=12），BK通道电导为（258±42）pS（n=6），在刺激电位150mV时，电流密度为（275±40）pA／pF（n=8）；在电极外液钙离子浓度为1μmol／L，刺激电位为0、20、40、60、80、100、120、140和160mV条件下，BK通道开放概率（NP0）分别为0、0．0002、0．0016±0．0005、0．0283±0．0081、0．05694±0．0102、0．3533±0．0514、1．4922±0．1578、2．5975±0．3632和4．6041±0．7834（P〈0．05，n=5）；在刺激电位60mV，电极外液钙离子浓度为0、0．001、0．01、0．1、1、10、50和100μmol／L条件下，BK通道NP。分别为0、0．0001、0．0031±0．0008、0．0042±0．0090、0．0808±0．0105、0．7591±0．1274、2．7242±0．4612和3．2366±0．5728（P〈0．05，n=6）。结论BK通道广泛分布于冠状动脉平滑肌细胞上，具有电压敏感性和钙敏感性，对冠状动脉血管张力调节起重要作用。
Objective To investigate characteristics of large conductance Ca2± -activated K ± currents （ BK currents） in normal rat coronary smooth muscle ceils. Methods Coronary smooth muscle cells were isola- ted by enzyme digestion. Potassium channels in coronary smooth muscle cells were identified by applications of different potassium blockers. BK currents were recorded by patch clamp in whole cell and single channel config- uration,respectively. BK currents amplitude and conductance were calculated. Vohage-sensitive and calcium- sensitive characteristics of BK currents and changes with IBTX,a specific blocker,were observed. Results BK currents in normal smooth muscle cells accounted for 65% ± 4% of total potassium currents （n = 12）, BK cur- rent conductance was（258 ± 42）pS（ n = 6 ）, and current densities were （275 ± 40）pA/pF at voltage 150 mV （ n = 8 ）. Open probabilities （ NP0 ） of BK channels at calcium 1 μmol/L in external solution and test potentials at 0,20,40,60,80,100,120,140 and 160 mV were 0,0. 0002,0. 0016 ± 0. 0005,0. 0283 ± 0. 0081,0. 05694 ±0. 0102,0. 3533 -± 0. 0514,1. 4922 ± 0. 1578,2. 5975 ±0. 3632, and 4. 6041 ±0. 7834, respectively （P 〈 0.05,n = 5 ）. NP0 of BK channels at test potential 60 mV, and calcium in external solution at 0,0. 001,0. 01,0. 1,1, 10,50 and 100 ixmol/L were 0,0. 0001,0. 0031 ± 0. 0008,0. 0042 ±_ 0. 0090,0. 0808 ±_ 0. 0105,0. 7591 ±0. 1274,2. 7242 ±_ 0. 4612,and 3. 2366 -± 0. 5728, respectively （ P 〈 0.05, n = 6 ）. Conclusion BK channels are widely distributed in normal coronary smooth muscle cells, have voltage-sensitive and calcium-sensitive characteristics, and play an important role in regulation of coronary vascular tension.
出处
《中华心律失常学杂志》
2011年第1期45-49,共5页
Chinese Journal of Cardiac Arrhythmias
基金
基金项目：国家自然科学基金（81070157）
关键词
大电导钙离子激活钾通道电流
电压敏感
钙敏感
冠状动脉
膜片钳
Large conductance Ca2 ＋ -activated K ＋ current
Voltage-sensitive
Calcium-sensitive
Coronary artery
Patch clamp
