Journal article
Enhanced Dispersion of Repolarization and Refractoriness in Transgenic Mouse Hearts Promotes Reentrant Ventricular Tachycardia
Circulation research, Vol.86(4), pp.396-407
03/03/2000
DOI: 10.1161/01.RES.86.4.396
PMID: 10700444
Abstract
ABSTRACTThe heterogeneous distribution of ion channels in ventricular muscle gives rise to spatial variations in action potential (AP) duration (APD) and contributes to the repolarization sequence in healthy hearts. It has been proposed that enhanced dispersion of repolarization may underlie arrhythmias in diseases with markedly different causes. We engineered dominant negative transgenic mice that have prolonged QT intervals and arrhythmias due to the loss of a slowly inactivating K current. Optical techniques are now applied to map APs and investigate the mechanisms underlying these arrhythmias. Hearts from transgenic and control mice were isolated, perfused, stained with di-4-ANEPPS, and paced at multiple sites to optically map APs, activation, and repolarization sequences at baseline and during arrhythmias. Transgenic hearts exhibited a 2-fold prolongation of APD, less shortening (8% versus 40%) of APDs with decreasing cycle length, altered restitution kinetics, and greater gradients of refractoriness from apex to base compared with control hearts. A premature impulse applied at the apex of transgenic hearts produced sustained reentrant ventricular tachycardia (n=14 of 15 hearts) that did not occur with stimulation at the base (n=8) or at any location in control hearts (n=12). In transgenic hearts, premature impulses initiated reentry by encountering functional lines of conduction block caused by enhanced dispersion of refractoriness. Reentrant VT had stable (>30 minutes) alternating long/short APDs associated with long/short cycle lengths and T wave alternans. Thus, optical mapping of genetically engineered mice may help elucidate some electrophysiological mechanisms that underlie arrhythmias and sudden death in human cardiac disorders.
Details
- Title: Subtitle
- Enhanced Dispersion of Repolarization and Refractoriness in Transgenic Mouse Hearts Promotes Reentrant Ventricular Tachycardia
- Creators
- Linda Baker - From the Department of Bioengineering (L.C.B.), Cardiovascular Institute (B.L.), and Department of Cell Biology and Physiology (B.-R.C., G.S.), University of Pittsburgh, Pittsburgh, Pa; and Division of Cardiology (G.K.), Brigham and Women’s Hospital, Boston, MassBarry LondonBum-Rak ChoiGideon KorenGuy Salama
- Resource Type
- Journal article
- Publication Details
- Circulation research, Vol.86(4), pp.396-407
- Publisher
- American Heart Association, Inc
- DOI
- 10.1161/01.RES.86.4.396
- PMID
- 10700444
- ISSN
- 0009-7330
- eISSN
- 1524-4571
- Language
- English
- Date published
- 03/03/2000
- Academic Unit
- Molecular Physiology and Biophysics; Cardiovascular Medicine; Internal Medicine
- Record Identifier
- 9984025592002771
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