Remodeling of the cardiac sodium channel, connexin 43, and plakoglobin at the intercalated disk in patients with arrhythmogenic cardiomyopathy.

Noorman, Maartje and Hakim, Sara and Kessler, Elise and Groeneweg, Judith A. and Cox, Moniek G. P. J. and Asimaki, Angeliki and Rijen, Harold V. M. van and Stuijvenberg, Leonie van and Chkourko, Halina and Heyden, Marcel A. G. van der and Vos, Marc A. and Jonge, Nicolaas de and Smagt, Jasper J. van der and Dooijes, Dennis and Vink, Aryan and Weger, Roel A. de and Varró, András and Bakker, Jacques M.T. de and Saffitz, Jeffrey E. and Hund, Thomas J. and Mohler, Peter J. and Delmar, Mario and Hauer, Richard N. W. and Veen, Toon A.B. van (2013) Remodeling of the cardiac sodium channel, connexin 43, and plakoglobin at the intercalated disk in patients with arrhythmogenic cardiomyopathy. HEART RHYTHM, 10 (3). pp. 412-419. ISSN 1547-5271

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Abstract

Background Arrhythmogenic cardiomyopathy (AC) is closely associated with desmosomal mutations in a majority of patients. Arrhythmogenesis in patients with AC is likely related to remodeling of cardiac gap junctions and increased levels of fibrosis. Recently, using experimental models, we also identified sodium channel dysfunction secondary to desmosomal dysfunction. Objective To assess the immunoreactive signal levels of the sodium channel protein NaV1.5, as well as connexin43 (Cx43) and plakoglobin (PKG), in myocardial specimens obtained from patients with AC. Methods Left and right ventricular free wall postmortem material was obtained from 5 patients with AC and 5 controls matched for age and sex. Right ventricular septal biopsies were taken from another 15 patients with AC. All patients fulfilled the 2010 revised Task Force Criteria for the diagnosis of AC. Immunohistochemical analyses were performed using antibodies against Cx43, PKG, NaV1.5, plakophilin-2, and N-cadherin. Results N-cadherin and desmoplakin immunoreactive signals and distribution were normal in patients with AC compared to controls. Plakophilin-2 signals were unaffected unless a plakophilin-2 mutation predicting haploinsufficiency was present. Distribution was unchanged compared to that in controls. Immunoreactive signal levels of PKG, Cx43, and NaV1.5 were disturbed in 74%, 70%, and 65% of the patients, respectively. Conclusions A reduced immunoreactive signal of PKG, Cx43, and NaV1.5 at the intercalated disks can be observed in a large majority of the patients. Decreased levels of Nav1.5 might contribute to arrhythmia vulnerability and, in the future, potentially could serve as a new clinically relevant tool for risk assessment strategies.

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