Document Detail


Architectural Correlates of Myocardial Conduction: Changes to the Topography of Cellular Coupling, Intracellular Conductance and Action Potential Propagation with Hypertrophy in Guinea-Pig Ventricular Myocardium.
MedLine Citation:
PMID:  25313260     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
BACKGROUND: -We tested the hypothesis that alterations to action potential conduction velocity (CV) and conduction anisotropy in left ventricular hypertrophy are associated with topographical changes to gap-junction coupling and intracellular conductance by measuring these variables in the same preparations.
METHODS AND RESULTS: -Left ventricular papillary muscles were excised from aortic-banded or sham-operated guinea-pig hearts. With intracellular stimulating and recording microelectrodes, CV was measured in three dimensions with simultaneous conductance mapping with subthreshold stimuli and correlated with quantitative histomorphometry of myocardial architecture and connexin43 (Cx43) distribution. In hypertrophied myocardium, CV in the longitudinal axis was smaller and transverse velocity greater compared to control; associated with similar differences of intracellular conductance, consistent with more cell contacts per cell (5.7±0.2 vs 8.1±0.5, control vs hypertrophy), and more intercalated disks mediating side-to-side coupling (8.2±0.2 vs 10.2±0.4 per cell). Intercalated disk morphology and Cx43 immunolabelling were not different in hypertrophy. Hypertrophied preparations showed local submillimeter (~250 μm) regions with very slow conduction and low intracellular conductance which, although not affecting CV on the millimeter scale, were consistent with discontinuities from increased microscopical connective tissue content.
CONCLUSIONS: -With myocardial hypertrophy, altered longitudinal and transverse CV, and greater non-uniformity of CV anisotropy correspond to changes of intracellular conductance. These are associated with alteration of myocardial architecture, specifically the topography of cell-cell coupling and gap-junction connectivity.
Authors:
Christopher H Fry; Rosaire P Gray; Paramdeep S Dhillon; Rita I Jabr; Emmanuel Dupont; Pravina M Patel; Nicholas S Peters
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-10-13
Journal Detail:
Title:  Circulation. Arrhythmia and electrophysiology     Volume:  -     ISSN:  1941-3084     ISO Abbreviation:  Circ Arrhythm Electrophysiol     Publication Date:  2014 Oct 
Date Detail:
Created Date:  2014-10-14     Completed Date:  -     Revised Date:  2014-10-15    
Medline Journal Info:
Nlm Unique ID:  101474365     Medline TA:  Circ Arrhythm Electrophysiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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