小鼠主动脉狭窄后不同时期心室肌细胞后除极和触发活动的变化

目的：探讨小鼠主动脉狭窄后不同时期心室肌细胞后除极和触发活动的变化及可能的机制。方法：复制小鼠主动脉狭窄模型后，取小鼠心脏，采用玻璃微电极技术，记录左心室乳头肌动作电位早后除极（EAD）、迟后除极（DAD）和触发活动情况，以及灌流低钾或异丙肾上腺素溶液后，所诱发后除极触发活动的变化。结果：①与同时期对照组比较，小鼠乳头肌动作电位APD90模型组2周和5周组保持不变，9周和13周明显延长。②在记录的30min时间内，模型组9周和13周动物出现EAD和DAD，而对照组以及模型组2周和5周动物未出现EAD和DAD。③低钾或异丙肾上腺素诱发EAD和DAD的发生率，模型组显著高于同期对照组，并且模型组动物的发生率随着时间进行性增加。结论：小鼠主动脉狭窄后，心肌细胞EAD、DAD以及触发活动逐渐增多，心肌细胞的电不稳定性逐渐增加。

Alterations of after depolarization and triggered activity in myocardiac muscle during progression of mouse aortic stenosis

Objective： To explore the alterations of after depolarization and triggered activity in myocardiac muscle during progression of mouse aortic stenosis. Methods： After the establishment of mouse aortic stenosis model, the heart was collected and intracellular potential was recorded using standard glass microelectrode. After the recording, the action potential （AP）, early after depolarization （EAD）, delayed after depolarization （DAD） in papillary muscles were analysed. Results： ① Compared with that of time-matched control mice, there were no changes of the action potoutial duration at 90% repolarization（APD90）in model mice at 2 and 5 weeks, whereas the APD90 was progressively prolonged at 9 and 13 weeks. ② During the 30 minites of the experiment, spontaneous EADs and DADs were frequently present in medel mice at 9 and 13 weeks, were not in control and model mice at 2 and 5 weeks.③compared with those of control group, EADs and DADs triggered by hypokalaemia or isoproterenol were increased significantly. The incidence rate of triggering EADs and DADs was progressively increased over time. Conclusion： EAD, DAD and trigger activities increase gradually during the process of aortic stenosis, and it suggests that the myocardium electrical-iustabihty is markedly increased in the insult hearts.