Downregulation of connexin40 and increased prevalence of atrial arrhythmias in transgenic mice with cardiac-restricted overexpression of tumor necrosis factor

Sam E. Sawaya, Yadavendra S. Rajawat, Tapan G. Rami, Gabor Szalai, Robert L. Price, Natarajan Sivasubramanian, Douglas L. Mann, Dirar S. Khoury

Research output: Contribution to journalArticle

68 Scopus citations

Abstract

Atrial arrhythmias, primarily atrial fibrillation, have been independently associated with structural remodeling and with inflammation. We hypothesized that sustained inflammatory signaling by tumor necrosis factor (TNF) would lead to alterations both in underlying atrial myocardial structure and in atrial electrical conduction. We performed ECG recording, intracardiac electrophysiology studies, epicardial mapping, and connexin immunohistochemical analyses on transgenic mice with targeted overexpression of TNF in the cardiac compartment (MHCsTNF) and on wild-type (WT) control mice (age 8-16 wk). Atrial and ventricular conduction abnormalities were always evident on ECG in MHCsTNF mice, including a shortened atrioventricular interval with a wide QRS duration secondary to junctional rhythm. Supraventricular arrhythmias were observed in five of eight MHCsTNF mice, whereas none of the mice demonstrated ventricular arrhythmias. No arrhythmias were observed in WT mice. Left ventricular conduction velocity during apical pacing was similar between the two mouse groups. Connexin40 was significantly downregulated in MHCsTNF mice. In contrast, connexin43 density was not significantly altered in MHCsTNF mice, but rather dispersed away from the intercalated disks. In conclusion, sustained inflammatory signaling contributed to atrial structural remodeling and downregulation of connexin40 that was associated with an increased prevalence of atrial arrhythmias.

Original languageEnglish
Pages (from-to)H1561-H1567
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume292
Issue number3
DOIs
StatePublished - Mar 1 2007
Externally publishedYes

Keywords

  • Atrial fibrillation
  • Electrophysiology
  • Heart failure

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