Referenced in: none

Automatically associated channels: Kv7.1 , Nav1.5

Title: Optical mapping of ventricular arrhythmias in LQTS mice with SCN5A mutation N1325S.

Authors: Xiao-Li Tian, Yuanna Cheng, Teng Zhang, Mei-Ling Chang Liao, Sandro L Yong, Qing K Wang

Journal, date & volume: Biochem. Biophys. Res. Commun., 2007 Jan 26 , 352, 879-83

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/17157817

Abstract
Transgenic expression of SCN5A mutation N1325S creates a mouse model for type-3 long QT syndrome (LQT3), TG-NS/LQT3. Optical mapping is a high temporal and spatial resolution fluorescence mapping system that records 256 action potentials simultaneously in a Langendorff-perfused heart. Here for the first-time, we provide a spatial view of VT in a genetic LQT3 model using optical mapping. Spontaneous VT was detected in TG-NS/LQT3 hearts, but not in littermate control hearts. VT was initiated primarily by activation of a new firing focus as well as functional conduction block of new activation waves. New firing was initiated at many different Loci in the heart, suggesting that "increased automaticity" is a key mechanism for initiation of VT. The sustained VT was maintained by a reentry mechanism. Nifedipine, an L-type calcium channel blocker, decreased the frequency of VT, indicating the involvement of abnormalities of the calcium homeostasis in the genesis of VT in TG-NS/LQT3 mice.