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The involvement of gap junctions in the delayed phase of the protection induced by cardiac pacing in dogs
- Source :
- Clinical Science. 123:39-51
- Publication Year :
- 2012
- Publisher :
- Portland Press Ltd., 2012.
-
Abstract
- The present study has examined the role of GJ (gap junctions) in the delayed anti-arrhythmic effect of cardiac pacing, with particular reference to the time-course changes in Cx43 (connexin43) expression both after pacing (4×5 min, at a rate of 240 beats/min) and 24 h later, when the dogs were subjected to a 25 min occlusion and reperfusion of the LAD (left anterior descending coronary artery). Compared with the SP (sham-paced) controls (n=20), in dogs paced 24 h previously (n=16) there were reductions in arrhythmia severity [e.g. number of VPB (ventricular premature beats) during occlusion 294±78 compared with 63±25; survival from the combined ischaemia/reperfusion insult 20% compared with 78%], and in other ischaemic changes [epicardial ST-segment, TAT (total activation time) and tissue impedance]. Pacing also prevented the ischaemia-induced structural impairment of the intercalated discs, and preserved GJ permeability and Cx43 phosphorylation, without modifying Cx43 protein content. Following cardiac pacing the membrane and total Cx43 protein contents were unchanged up to 6 h, but were significantly reduced 12 h later (preceded by a down-regulation of Cx43 mRNA at 6 h), and returned to normal by 24 h. Interestingly, dogs that were subjected to ischaemia 12 h after cardiac pacing showed increased arrhythmia generation. We conclude that cardiac pacing results in time-dependent changes in Cx43 expression, which may alter GJ function and influence arrhythmia generation during a subsequent ischaemia/reperfusion insult. This effect is manifested in protection 24 h 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.
- Subjects :
- Male
medicine.medical_specialty
Cardiac pacing
Blotting, Western
Ischemia
Fluorescent Antibody Technique
Anterior Descending Coronary Artery
Protein content
Dogs
Internal medicine
Occlusion
Animals
Medicine
Tissue impedance
business.industry
Myocardium
Cardiac Pacing, Artificial
Gap junction
Gap Junctions
General Medicine
Delayed phase
medicine.disease
Coronary Occlusion
Connexin 43
Reperfusion Injury
Anesthesia
Ischemic Preconditioning, Myocardial
Ventricular Fibrillation
Tachycardia, Ventricular
cardiovascular system
Cardiology
Female
business
Subjects
Details
- ISSN :
- 14708736 and 01435221
- Volume :
- 123
- Database :
- OpenAIRE
- Journal :
- Clinical Science
- Accession number :
- edsair.doi.dedup.....e78a89ad3215edd8788b9300b60a06f4