Inducibility of abnormal automaticity and triggered activity in myocardial sleeves of canine pulmonary veins

Tsui Min Wang, Hsiang Ning Luk, Joen Rong Sheu, Hsiao Ping Wu, Chern En Chiang

研究成果: 雜誌貢獻文章同行評審

19 引文 斯高帕斯(Scopus)

摘要

Background: To study the cellular mechanisms governing cardiac atrial arrhythmias initiated by ectopic focus (or foci) from pulmonary veins (PVs). Methods: In the present in vitro study, we applied the conventional microelectrode technique to record intracellular action potentials in PV sleeves from dogs. Results: In 80 normal healthy dogs, all action potentials recorded in cardiomyocytes from PV sleeves were fast-response. The pharmacological responses to quinidine, nisoldipine, d-sotalol, 4-aminopyridine, isoproterenol, acetylcholine, and adenosine were characteristic of those in atrial cells. Diastolic depolarization and spontaneous activity could be induced by 1 mmol/L Ba2+ in all the 22 PV specimens being tested, but only in 3 of 11 of left atrial specimens (p2+, the diastolic slope was only slightly affected by Ni2+ (500 μmol/L), but was significantly suppressed by Cd2+ (200 μmol/L). Ryanodine (2 μmol/L) caused a transient increase, followed by a marked decrease of Ba2+-induced spontaneous activity. Isoproterenol shortened and acetylcholine prolonged the cycle length of the Ba 2+-induced automatic activity. In the presence of isoproterenol, washout of acetylcholine induced a rebound phenomenon, which triggered a short period of spontaneous activity. The results suggest an important role of intracellular cytoplasmic Ca2+ loading. Under conditions that mimic ischemia/hypoxia, the resting membrane potential depolarized, upstroke of the action potential became depressed and the action potential duration shortened. In the presence of isoproterenol and elevated external K+, spontaneous activity was generated. Conclusions: These findings indicate a lack of arrhythmogenic activity in normal healthy PV sleeves. Abnormal automaticity and triggered activity occurred exclusively under simulated pathologic conditions. Ba2+-induced automaticity was more easily induced in PV than in the left atrium. The same conditions might also favor the genesis of reentry in the in vivo condition.

原文英語
頁(從 - 到)59-66
頁數8
期刊International Journal of Cardiology
104
發行號1
DOIs
出版狀態已發佈 - 九月 15 2005

ASJC Scopus subject areas

  • 心臟病學與心血管醫學

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