Document Detail


Adrenergic Deficiency Leads to Impaired Electrical Conduction and Increased Arrhythmic Potential in the Embryonic Mouse Heart.
MedLine Citation:
PMID:  22683331     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
To determine if adrenergic hormones play a critical role in the functional development of the cardiac pacemaking and conduction system, we employed a mouse model where adrenergic hormone production was blocked due to targeted disruption of the dopamine β-hydroxylase (Dbh) gene. Immunofluorescent histochemical evaluation of the major gap junction protein, connexin 43, revealed that its expression was substantially decreased in adrenergic-deficient (Dbh(-/-)) relative to adrenergic-competent (Dbh(+/+) and Dbh(+/-)) mouse hearts at embryonic day 10.5 (E10.5), whereas pacemaker and structural protein staining appeared similar. To evaluate cardiac electrical conduction in these hearts, we cultured them on microelectrode arrays (8x8, 200 μm apart). Our results show a significant slowing of atrioventricular conduction in adrenergic-deficient hearts compared to controls (31.4 ± 6.4 vs. 15.4 ± 1.7 ms, respectively, p < 0.05). To determine if the absence of adrenergic hormones affected heart rate and rhythm, mouse hearts from adrenergic-competent and deficient embryos were cultured ex vivo at E10.5, and heart rates were measured before and after challenge with the β-adrenergic receptor agonist, isoproterenol (0.5 μM). On average, all hearts showed increased heart rate responses following isoproterenol challenge, but a significant (p < 0.05) 225% increase in the arrhythmic index (AI) was observed only in adrenergic-deficient hearts. These results show that adrenergic hormones may influence heart development by stimulating connexin 43 expression, facilitating atrioventricular conduction, and helping to maintain cardiac rhythm during a critical phase of embryonic development.
Authors:
Candice Baker; David G Taylor; Kingsley Osuala; Anupama Natarajan; Peter J Molnar; James Hickman; Sabikha Alam; Brittany Moscato; David Weinshenker; Steven N Ebert
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-6
Journal Detail:
Title:  Biochemical and biophysical research communications     Volume:  -     ISSN:  1090-2104     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-6-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372516     Medline TA:  Biochem Biophys Res Commun     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier Inc.
Affiliation:
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Blvd, Orlando, FL 32827.
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