Apamin induces early afterdepolarizations and torsades de pointes ventricular arrhythmia from failing rabbit ventricles exhibiting secondary rises in intracellular calcium

Po Cheng Chang, Yu Cheng Hsieh, Chia Hsiang Hsueh, James N. Weiss, Shien-Fong Lin, Peng Sheng Chen*

*Corresponding author for this work

研究成果: Article同行評審

52 引文 斯高帕斯(Scopus)

摘要

Background A secondary rise of intracellular Ca2+ (Ca i) and an upregulation of apamin-sensitive K+ current (IKAS) are characteristic findings of failing ventricular myocytes. We hypothesize that apamin, a specific IKAS blocker, may induce torsades de pointes (TdP) ventricular arrhythmia from failing ventricles exhibiting secondary rises of Cai. Objective To test the hypothesis that small conductance Ca2+ activated IKAS maintains repolarization reserve and prevents ventricular arrhythmia in a rabbit model of heart failure (HF). Methods We performed Langendorff perfusion and optical mapping studies in 7 hearts with pacing-induced HF and in 5 normal control rabbit hearts. Atrioventricular block was created by cryoablation to allow pacing at slow rates. Results The left ventricular ejection fraction reduced from 69.1% [95% confidence interval 62.3%-76.0%] before pacing to 30.4% [26.8%-34.0%] (N = 7; P <.001) after pacing. The corrected QT interval in failing ventricles was 337 [313-360] ms at baseline and 410 [381-439] ms after applying 100 nmol/L of apamin (P =.01). Apamin induced early afterdepolarizations (EADs) in 6 ventricles, premature ventricular beats (PVBs) in 7 ventricles, and polymorphic ventricular tachycardia consistent with TdP in 4 ventricles. The earliest activation site of EADs and PVBs always occurred at the site with long action potential duration and large amplitude of the secondary rises of Cai. Apamin induced secondary rises of Ca i in 1 nonfailing ventricle, but no EAD or TdP were observed. Conclusions In HF ventricles, apamin induces EADs, PVBs, and TdP from areas with secondary rises of Cai. IKAS is important in maintaining repolarization reserve and preventing TdP in HF ventricles.

原文English
頁(從 - 到)1516-1524
頁數9
期刊Heart Rhythm
10
發行號10
DOIs
出版狀態Published - 十月 2013

指紋 深入研究「Apamin induces early afterdepolarizations and torsades de pointes ventricular arrhythmia from failing rabbit ventricles exhibiting secondary rises in intracellular calcium」主題。共同形成了獨特的指紋。

引用此