Document Detail

The involvement of gap junctions in the delayed phase of the protection induced by cardiac pacing in dogs.
MedLine Citation:
PMID:  22242938     Owner:  NLM     Status:  Publisher    
This study has examined the role of gap junctions in the delayed anti-arrhythmic effect of cardiac pacing, with particular reference to the time-course changes in connexin43 (Cx43) expression both after pacing (4x5 min, at a rate of 240 beats min-1) and 24h later, when the dogs were subjected to a 25 min occlusion and reperfusion of the left anterior descending coronary artery. Compared to the sham-paced controls (n=20), in dogs paced 24h previously (n=16) there were reductions in arrhythmia severity (e.g. number of ventricular premature beats during occlusion 294±78 vs. 63±25; survival from the combined ischaemia/reperfusion insult 20% vs. 78%), and in other ischaemic changes (epicardial ST-segment, total activation time, tissue impedance). Pacing also prevented the ischaemia-induced structural impairment of the intercalated discs, and preserved gap junction permeability and Cx43 phosphorylation, without modifying Cx43 protein contents. Following cardiac pacing the membrane and total Cx43 protein contents were unchanged up to 6h, but significantly reduced 12h later (preceded by a down-regulation of Cx43 mRNA at 6h), and returned to normal by 24h. Interestingly, dogs that were subjected to ischaemia 12h after cardiac pacing showed increased arrhythmia generation. We conclude that cardiac pacing results in time-dependent changes in Cx43 expression, which may alter gap junction function and influence arrhythmia generation during a subsequent ischaemia/reperfusion insult. This effect is manifested in protection 24h after pacing, but of potential clinical interest is the finding, that there is a time interval after pacing during which an ischaemic event may generate severe ventricular arrhythmias.
Márton Gönczi; Mária Kovács; György Seprényi; Agnes Végh
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-16
Journal Detail:
Title:  Clinical science (London, England : 1979)     Volume:  -     ISSN:  1470-8736     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7905731     Medline TA:  Clin Sci (Lond)     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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