牵拉刺激对豚鼠心室肌动作电位时程的影响及其机制  

Effects of mechanical stretch on action potential duration in isolated guinea-pig ventricular myocytes and the mechanism

作　　者：张知非[1] 钮伟真[1] 

机构地区：[1]100054北京市

出　　处：《中国心血管病研究》2005年第4期304-308,共5页Chinese Journal of Cardiovascular Research

摘　　要：目的本实验观察了牵拉刺激对离体豚鼠左心室乳头肌动作电位的影响,为探讨心肌牵张激活离子通道电流的特点提供实验依据。方法实验采用标准微电极细胞内记录技术引导豚鼠心室乳头肌细胞动作电位,用微机化生理信号采集分析系统(NSA-Ⅲ)记录并处理信号。结果①牵拉心肌可加快整个复极过程,APD20、APD50和APD90均有缩短(P<0.05)。牵拉作用呈心肌长度依赖性。牵拉刺激对RP和APA无显著性影响(P>0.05)。②内向整流钾通道(IK1)阻断剂BaCl2(100μmol/L)可明显减弱因牵拉刺激导致的动作电位时程缩短。应用格列本脲、奎尼丁和氯化钆与未用药组比较无显著差异(P>0.05)。结论①在豚鼠心室肌存在牵拉刺激激活的外向电流,这种电流加快复极过程,使动作电位时程明显缩短。②该电流可能与内向整流钾通道(IK1)有关,但是与ATP敏感性钾通道和IKr无关。Objective In order to explore the characteristics of stretch-activated ion current, the effects of mechanical stretch on guinea pig ventricular myocytes was investigated. Methods Conventional microelectrodes were used to record the action potentials (AP) of isolated ventricular papillary muscles. NSA-Ⅲ system was used to record and process the signals. Results The results showed that the mechanical stretch accelerated repolarization of ventricular myocytes length-dependently. Stretch stimulation had no obvious effect on the resting potential and amplitude of AP. Inward rectification potassium ion channel (IK1) blocker, BaCl2 (100μmol / L), obviously weakened the shortening trend of APD induced by stretch stimulation. Conclusion These results indicate: ①There were stretch-activated outward currents, which accelerated repolarization and obviously shortened the action potential duration. ②The currents may be related with inward rectification potassium channel, but had nothing to do with ATP-sensitive potassium channel and IKr.

关 键 词：机械电反馈 牵张激活离子通道 动作电位 内向整流钾通道 

分 类 号：R331.38[医药卫生—人体生理学]