糖尿病大鼠冠状动脉平滑肌细胞大电导钙激活钾通道特性及开放动力学的变化  

Change of large-conductance calcium-activated potassium channel activities and dynamics in diabetes mellitus

作　　者：钱玲玲[1] 刘晓宇[1] 孙曼青[1] 夏大云[1] 汤徐 季圆[1] 吴莹[1] 党时鹏[1] 柴强[2] 王如兴[1] 

机构地区：[1]南京医科大学附属无锡人民医院心内科,江苏无锡214023 [2]山东省医学科学院基础医学研究所心血管病研究室,山东济南250062

出　　处：《中国心脏起搏与心电生理杂志》2017年第4期343-347,共5页Chinese Journal of Cardiac Pacing and Electrophysiology

基　　金：国家自然科学基金(81370303;81500249);江苏省自然科学基金(BK20151110);江苏省人事厅"六大人才高峰"第七批高层次项目(006);江苏省医学重点人才资助项目(RC201134);南京医科大学科技发展基金重点项目(2013NJMU153)

摘　　要：目的研究糖尿病时冠状动脉平滑肌细胞大电导钙激活钾通道(BK通道)的电压依赖性、钙敏感性及其开放动力学变化,探讨糖尿病时冠状动脉损伤的细胞电生理机制。方法采用链脲霉素腹腔内注射建立糖尿病大鼠模型(糖尿病组,n=30),对照组相应注射生理盐水(n=30);采用酶消化法急性分离大鼠冠状动脉平滑肌细胞;采用膜内向外型单通道膜片钳实验技术记录BK单通道电流;采用Clampfit 10.4软件分析单通道数据。结果在电极外液钙离子浓度为1mmol/L,刺激电位分别为0,20,40,60,80,100,120和140mV时,随着刺激电位增加,正常组BK通道的NPo逐渐增加,其半数有效激活电压(V1/2)为(88.45±1.72)mV;糖尿病组BK通道NPo亦逐渐增加,V1/2为(104.29±1.09)mV,其电压-NPo曲线较正常组向左下移动。在刺激电位60 mV,电极外液钙离子浓度分别为0,0.01,0.1,0.5,1,5,10和50mmol/L时,随着电极外液钙离子浓度增加,正常组BK通道NPo逐渐增加,其半数有效激活浓度(EC50)为(2.26±0.27)mmol/L;糖尿病组BK通道NPo亦逐渐增加,EC50为(3.15±0.20)mmol/L,其浓度-NPo曲线较正常组向左下移动。在电极外液钙离子浓度为1mmol/L,刺激电位60 mV时,与正常组比较,糖尿病组BK通道NPo明显减少,电流幅度与平均开放时间无明显变化,而平均关闭时间显著延长[(451.35±113.71)ms vs(107.58±15.99)ms,P<0.05]。结论糖尿病时冠状动脉平滑肌细胞BK通道电压依赖性与钙敏感性均受损,开放概率减少,通道平均关闭时间延长,这可能是糖尿病冠状动脉功能损伤的重要原因之一。Objective To investigate large-conductance calcium-activated potassium （BK） channel activities inclu- ding voltage dependence and Ca2＋ dependence, and open dynamics in rat coronary smooth muscle cells in diabetes mellitus. Methods The diabetic models were established by intraperitoneally injecting streptozotocin in Sprague Dawley rats. Thirty diabetic rats and 30 control rats were abtained in this study. Coronary smooth muscle cells were isolated by enzyme digestion. Single BK currents were recorded by patch clamp in inside-out single channelconfiguration. The data of single BK currents was anal- ysised using Clampfit 10.4 software. Results At 1 mmol/L calcium in external solution and test potentials at 0, 20, 40, 60, 80, 100, 120 and 140 mV, open probabilities （NPo） of normal BK channel were in- creased with the increase of the stimulation potential, the voltage at half maximal effect （V1/2） was （104.29 ±1.09） inV. NPo of diabetic BK channel were also in- creased with the increase of the stimulation potential The V1/2 was （ 8 8.4 5±1.7 2 ） mV and the voltage- Ni＇ocurve moved to the left of the normal group. At 60 mV and 0, 0.01, 0.1, 0.5, 1, 5, 10 and 50 mmol/L calcium in external solution, NPo＇ of normal BK channel were increased with the increase of the calcium concentration, the con- centration at half maximal effect （ECs0） was （2.26 ± 0.27） mmol/L ; NPo of diabetic BK channel were also increased with the increase of the calcium concentration. The ECs0 was （3.15±0.20） mmol/L the concentration-NPo curve moved to the left of the normal group. At 1 mmol/L calcium in external solution and test potentials at 60 mV, NPo was decreased, close dwell-time was increased and current amplitude and open dwell time were not changed in dia- betic rats compared with normal rats. Conclusion In coronary artery smooth muscle cells, BK channel voltage de- pendence and Ca2＋ dependence are impaired, NPo is decreased and close dwell-time is prolonged in diabetic rats corn pared with normal

关 键 词：心血管病学 糖尿病 大电导钙激活钾通道 电压依赖性 钙敏感性 开放动力学 

分 类 号：R587.1[医药卫生—内分泌] R331.3[医药卫生—内科学]