Generation of reentrant arrhythmias by dominant-negative inhibition of connexin43 in rat cultured myocyte monolayers.
OBJECTIVE
Alteration of connexin43 (Cx43)-mediated intercellular communication is known to promote susceptibility to ventricular tachyarrhythmias. However, the precise mechanism of the altered Cx43 responsible for arrhythmogenesis remains unclear. We sought to understand changes in impulse propagation of ventricular myocytes under dominant-negative (DN) inhibition of Cx43 in the development of arrhythmias.


RESULTS
Intercellular communication was inhibited in confluent monolayers of neonatal rat cultured myocytes by an adenoviral vector-mediated gene transfer for DNCx43-fused red fluorescence protein (RFP). A high-resolution, macro-zoom fluorescence imaging system was used to visualize both the fluo4- and RFP-fluorescence intensities as measures of Ca2+ transient propagation and distribution of DNCx43 inhibition, respectively, in the myocyte monolayers. DNCx43 inhibition of the monolayers resulted in not only a significant slowing of Ca2+ transient propagation velocity, but also a preferential emergence of spiral-wave reentrant arrhythmias elicited by rapid pacing. Detailed observations on the development of spiral waves revealed that the gene-transferred myocyte monolayers exhibited regional slowing of propagation and subsequent generation of wave break, resulting in reentrant arrhythmias. Furthermore, DNCx43-RFP-transferred monolayers showed higher fluorescence intensity of RFP at the break point than at the surrounding myocardium, indicating a culprit role of DNCx43 inhibition in the genesis of spiral reentry.


CONCLUSIONS
The present results indicate that regional heterogeneity in gap-junctional communication promotes, in addition to slowing of conduction velocity, susceptibility to reentrant tachyarrhythmias.
Nakagami
Takuo
T
Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kawaramachi Hirokoji, Kyoto 602-8566, Japan.
Tanaka
Hideo
H
Dai
Ping
P
Lin
Shien-Fong
SF
Tanabe
Takuji
T
Mani
Hiroki
H
Fujiwara
Katsuji
K
Matsubara
Hiroaki
H
Takamatsu
Tetsuro
T
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D002478:Cells, Cultured; D018031:Connexin 43 / Q000037:antagonists & inhibitors* / Q000235:genetics; D017629:Gap Junctions / Q000502:physiology; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000209:etiology* / Q000378:metabolism / Q000473:pathology
D018031:Connexin 43; D002118:Calcium