动脉粥样硬化兔血管平滑肌钙激活钾通道活性和α亚单位表达的变化

The function of MaxiK channel increase and expression of the channel alpha subunit decrease with atherosclerosis in the rabbit arota.

目的研究动脉粥样硬化(atherosclerosis,AS)时血管平滑肌细胞(vascular smooth muscle cells,VSMC)大电导钙激活钾通道(big conductance Ca2+-activated K+-channel,BKCa)活性和α亚单位表达的变化及意义。方法高脂饮食建立兔动脉粥样硬化动物模型,利用膜片钳单通道记录技术记录AS组和对照组VSMC BKCa开放概率(Po),平均关闭时间(Tc)。应用实时荧光定量PCR技术分析BKcaα亚单位编码基因KCMA1的mRNA表达水平。结果①在cell-attachedpatches(膜电位+40mV)下,AS组和对照组的平均关闭时间(Tc)分别为(114.644±48.379)ms和(291.603±180.075)ms(P<0.001,n=10),开放概率(Po)分别为(0.1325±0.0555)和(0.0601±0.0433)(P<0.01,n=10);在inside-out patches(膜电位+40mV)下,二者的Tc为(69.075±37.711)ms和(396.876±177.161)ms(P<0.001,n=10),Po为(0.1676±0.1174)和(0.0409±0.177)(P<0.01,n=10);②AS组BKcaα亚单位表达减少。动脉粥样硬化兔KCMA1和GAPDH相对含量比为(0.68±0.5);对照组(3.19±2.14)。结论兔胸主动脉VSMC BKca在AS时α亚单位表达减少,但活性显著增强;BKca的活动可能作为AS时血管内皮源性舒张受损的一种选择性补偿机制,延缓动脉粥样硬化的进程。

Objective To evaluate the Function of MaxiK channel increase with atherosclerosis in the rabbit arota and explore molecular evidence of MaxiK channel alpha subnit decrease simultaneously.Methods Atherosclerosis models were induced by high lipid diet in rabbits.The single channel Patch-Clamp technique was adopted to record activity of VSMC BKca.Real-teim PCR was performed to verify Hslo gene expression.Results ①In cell-acttached patches（membrane potential was＋40mV）,the mean close time（Tc）of BKca for the AS group and the control group was（114.644±48.379）ms and（291.603±180.075）ms respectively（P〈0.001 n=10）,the open probability（Po）of the two was（0.1325±0.0555）and（0.0601±0.0433）respectively（P〈0.01 n=10）.Under inside-out patches（membrane potential was ＋40mV）,the Tc of BKca of the two groups was（69.075±37.711） VS（396.876±177.16）ms（P〈0.001 n=10）,the Po was（0.1566±0.0677） VS（0.0171±0.0076）,（P〈0.01 n=10）.②Although the expression of alpha subunit was decreased,the ratio of KCMA1 to GAPDH were（06.8±0.5） and（3.19±2.14） in AS and normal rabbits respectively.Conclusion The activity of VSMC BKca is distinctly higher than that of normal rabbits.Maxik selectively compensate for impaired endothelium-dependent relaxation in AS and prevent the process of AS.