豚鼠心室肌细胞Ikr快速失活过程的直接测定及意义

Direct measurement of the fast inactivation of I kr in guinea pig ventricular myocytes

目的：直接测定豚鼠心室肌细胞Ｉｋｒ的失活过程．方法：在全细胞电压钳制下采用间期很短（３０ｍｓ）的双刺激法进行观察．结果：Ｉｋｒ的失活过程时程短（＜２０ｍｓ），速度快（从－２０ｍＶ到＋８０ｍＶ），呈电压依赖性．结论：Ｉｋｒ的内向整流作用是由其失活过程所致．双刺激法直接测定技术能更好地模拟心律失常过程。

Objective: To measure directly the fast inactivation of I kr in single guinea pig ventricular myocytes. Methods: Whole cell patch clamp techniques and two pulse protocol (interval was 30 ms) were used. Results: The inactivation of I kr in single guinea pig ventricular myocytes occurred very fast (<20 ms) and was voltage dependent (from -20 mV to +80 mV). Conclusion: The inward rectification of I kr is due to its fast inactivation. The two pulse protocol can imitate premature beat occurred clinically. With this techniques, we can directly measure the inactivation of I kr , and it has important meaning in the studies of arrhythmia mechanisms and antiarrhythmia drugs.