钡离子(Ba~■)诱发心室肌细胞自发电活动的实验

SPONTANEOUS ELECTRICAL ACTIVITY INDUCED BY BARIUM IN ISOLATED GUINEA PIG VENTRICULAR MUSCLE

用心肌细胞跨膜电位记录,证实高浓度Ba~■(4mol/L)可诱发豚鼠心室肌自发电活性,这种自发电活性主要来自延迟后除极电位(DAD)及触发活动,且可被维拉帕米(异搏定)阻断,提示DAD的产生与钙离子内流有关。

Using standard intracellular potential recording method, we observed the electrophysiologic characteristics of spontaneous electrical activity induced by high concentration barium (Ba^(?), 4 mmol/L) in isolated guinea pig ventricular muscle as well as the influence of tetrodoxin (TTX) and verapamil. The results showed: (1) Ba^(?) significantly decreased resting potential (RP) to-61.33 mV and lengthened action potential duration of the ventricular mnscle; (2) Spontaneous electrical activity was induced in all of the 15 ventricular muscle preparations by Ba^(?), in which 7 preparations manifested as sustained triggered activities resulted from delayed after-depolarizations (DAD); (3) TTX had little effect, but verapamil had significant depressing effect on spontaneous electrical activity as well as DAD. It is concluded that DAD and triggered activity may be one of the important mechanisms responsible for spontaneous electrical activity induced by extracellular high concentration Ba^(?). Inward calcium current plays an important role in the generation of spontaneous electrical activity.