Document Detail

Knockout of the neural and heart expressed gene HF-1b results in apical deficits of ventricular structure and activation.
MedLine Citation:
PMID:  15907824     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Knockout of the neural and cardiac expressed transcription factor HF-1b causes electrophysiological abnormalities including fatal ventricular arrhythmias that occur with increasing frequency around the 4th week of postnatal life. This study addresses factors that may contribute to conduction disturbance in the ventricle of the HF-1b knockout mouse. Disruptions to gap junctional connexin40 (Cx40) have been reported in distal (i.e., apically located), but not proximal His-Purkinje conduction tissues of the HF-1b knockout mouse. This abnormality in myocardial Cx40 led us to address whether 4-week-old HF-1b knockout postnates display other disruptions to ventricular structure and function.
METHODS: Western blotting and immunoconfocal quantification of Cx43 and coronary arteriole density and function were undertaken in the ventricle. Electrical activation was described by optical mapping.
RESULTS: Western blotting and immunoconfocal microscopy indicated that overall levels of Cx43 (p<0.001) and percent of Cx43 localized in intercalated disks (p<0.001) were significantly decreased in the ventricular myocardium of knockouts relative to wildtype littermate controls. Analysis of the reduction in Cx43 level by basal and apical territories revealed that the decrease was most pronounced in the lower, apical half of the ventricle of knockouts relative to controls (p<0.001). Myocyte size also showed a significant decrease in the knockout, that was more marked within the apical half of the ventricle (p<0.05). Optical recordings of ventricular activation indicated apically localized sectors of slowed conduction in knockout ventricles not occurring in controls that could be correlated directly to tissues showing reduced Cx43. These discrete sectors of abnormal conduction in the knockout heart were resolved following point stimulation of the ventricular epicardium and thus were not explained by dysfunction of the His-Purkinje system. To further probe base-to-apex abnormalities in the HF-1b knockout ventricle, we analyzed coronary arterial structure and function. These analyses indicated that relative to controls, the apical ventricular territory of the HF-1b knockout had reductions in the density of small resistance vessels (p<0.01) and deficits in arterial function as assayed by bead perfusion (p<0.01).
CONCLUSION: The HF-1b knockout ventricle displays abnormalities in Cx43 level, myocyte size, activation spread and coronary arterial structure and function. These abnormalities tend to be more pronounced in the apical territory of the ventricle and seem likely to be factors contributing to the pathological disturbance of cardiac conduction that characterizes the heart of the HF-1b knockout mouse.
Kenneth W Hewett; Lisa W Norman; David Sedmera; Ralph J Barker; Charles Justus; Jing Zhang; Steven W Kubalak; Robert G Gourdie
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cardiovascular research     Volume:  67     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-25     Completed Date:  2006-01-13     Revised Date:  2014-03-19    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  548-60     Citation Subset:  IM    
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MeSH Terms
Actins / analysis
Biological Markers / analysis
Blotting, Western / methods
Cell Size
Connexin 43 / analysis
Coronary Vessels / metabolism,  pathology
Heart Conduction System
Heart Ventricles
Mice, Knockout
Myocytes, Cardiac / metabolism,  pathology*
Sp4 Transcription Factor / analysis,  genetics*
Ventricular Fibrillation / genetics*,  metabolism,  pathology
Grant Support
Reg. No./Substance:
0/Actins; 0/Biological Markers; 0/Connexin 43; 0/Sp4 Transcription Factor

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

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