Document Detail

Effect of activation sequence on transmural patterns of repolarization and action potential duration in rabbit ventricular myocardium.
MedLine Citation:
PMID:  20889843     Owner:  NLM     Status:  MEDLINE    
Although transmural heterogeneity of action potential duration (APD) is established in single cells isolated from different tissue layers, the extent to which it produces transmural gradients of repolarization in electrotonically coupled ventricular myocardium remains controversial. The purpose of this study was to examine the relative contribution of intrinsic cellular gradients of APD and electrotonic influences to transmural repolarization in rabbit ventricular myocardium. Transmural optical mapping was performed in left ventricular wedge preparations from eight rabbits. Transmural patterns of activation, repolarization, and APD were recorded during endocardial and epicardial stimulation. Experimental results were compared with modeled data during variations in electrotonic coupling. A transmural gradient of APD was evident during endocardial stimulation, which reflected differences previously seen in isolated cells, with the longest APD at the endocardium and the shortest at the epicardium (endo: 165 ± 5 vs. epi: 147 ± 4 ms; P < 0.05). During epicardial stimulation, this gradient reversed (epi: 162 ± 4 vs. endo: 148 ± 6 ms; P < 0.05). In both activation sequences, transmural repolarization followed activation and APD shortened along the activation path such that significant transmural gradients of repolarization did not occur. This correlation between transmural activation time and APD was recapitulated in simulations and varied with changes in intercellular coupling, confirming that it is mediated by electrotonic current flow between cells. These data suggest that electrotonic influences are important in determining the transmural repolarization sequence in rabbit ventricular myocardium and that they are sufficient to overcome intrinsic differences in the electrophysiological properties of the cells across the ventricular wall.
Rachel C Myles; Olivier Bernus; Francis L Burton; Stuart M Cobbe; Godfrey L Smith
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-10-01
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  299     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-03     Completed Date:  2011-01-13     Revised Date:  2013-07-03    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H1812-22     Citation Subset:  IM    
British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
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MeSH Terms
Action Potentials* / drug effects
Carbenoxolone / pharmacology
Cardiac Pacing, Artificial*
Cell Communication* / drug effects
Computer Simulation
Heart Ventricles / metabolism
Models, Cardiovascular
Myocardium / metabolism*
Oligopeptides / pharmacology
Time Factors
Grant Support
//British Heart Foundation
Reg. No./Substance:
0/Oligopeptides; 5697-56-3/Carbenoxolone; GFA1W6KO7N/rotigaptide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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