Electrical coupling and propagation in engineered ventricular myocardium with heterogeneous expression of connexin43.
Circ Res
; 110(11): 1445-53, 2012 May 25.
Article
em En
| MEDLINE
| ID: mdl-22518032
ABSTRACT
RATIONALE Spatial heterogeneity in connexin (Cx) expression has been implicated in arrhythmogenesis. OBJECTIVE:
This study was performed to quantify the relation between the degree of heterogeneity in Cx43 expression and disturbances in electric propagation. METHODS ANDRESULTS:
Cell pairs and strands composed of mixtures of Cx43(-/-) (Cx43KO) or GFP-expressing Cx43(+/+) (WT(GFP)) murine ventricular myocytes were patterned using microlithographic techniques. At the interface between pairs of WT(GFP) and Cx43KO cells, dual-voltage clamp showed a marked decrease in electric coupling (approximately 5% of WT) and voltage gating suggested the presence of mixed Cx43/Cx45 channels. Cx43 and Cx45 immunofluorescence signals were not detectable at this interface, probably because of markedly reduced gap junction size. Macroscopic propagation velocity, measured by multisite high-resolution optical mapping of transmembrane potential in strands of cells of mixed Cx43 genotype, decreased with an increasing proportion of Cx43KO cells in the strand. A marked decrease in conduction velocity was observed in strands composed of <50% WT cells. Propagation at the microscopic scale showed a high degree of dissociation between WT(GFP) and Cx43KO cells, but consistent excitation without development of propagation block.CONCLUSIONS:
Heterogeneous ablation of Cx43 leads to a marked decrease in propagation velocity in tissue strands composed of <50% cells with WT Cx43 expression and marked dissociation of excitation at the cellular level. However, the small residual electric conductance between Cx43 and WT(GFP) myocytes assures excitation of Cx43(-/-) cells. This explains the previously reported undisturbed contractility in tissues with spatially heterogeneous downregulation of Cx43 expression.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Comunicação Celular
/
Conexina 43
/
Miócitos Cardíacos
/
Acoplamento Excitação-Contração
/
Ventrículos do Coração
/
Junções Intercelulares
/
Contração Miocárdica
Limite:
Animals
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article