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Int J Clin Exp Pathol 2013;6(9):1874-1879

Original Article
Immunohistochemical evaluation of cardiac connexin43 in rats exposed to
low-frequency noise

Eduardo Antunes, Gonçalo Borrecho, Pedro Oliveira, José Brito, Artur Águas, José Martins dos Santos

Center for Interdisciplinary Research Egas Moniz, Health Sciences Institute, Monte de Caparica, Portugal; Department of Anatomy and UMIB of
ICBAS, Abel Salazar Institute for Biomedical Sciences, University of Porto, Porto, Portugal

Received July 11, 2013; Accepted July 26, 2013; Epub August 15, 2013; Published September 1, 2013

Abstract: Introduction: Low-frequency noise (LFN) leads to an abnormal proliferation of collagen and development of tissue fibrosis. It has
been shown that myocardial fibrosis in association with gap junction remodeling occurs in several cardiac diseases and can be implicated in
the development of ventricular tachyarrhythmias. We previously reported a strong development of myocardial fibrosis induced by LFN in rats but
it is not known whether LFN induces any modification on cardiac connexin43 (Cx43). Objectives: The aim of this study was to evaluate
modifications on cardiac Cx43 induced by LFN in Wistar rats. Methods: Two groups of rats were considered: A LFN-exposed group with 10 rats
submitted continuously to LFN during 3 months and a control group with 8 rats. The hearts were sectioned from the ventricular apex to the atria
and the mid-ventricular fragment was selected. The immunohistochemical evaluation of Cx43 was performed using the polyclonal antibody
connexin-43m diluted 1:1000 overnight at 4°C. Quantifications of Cx43 and muscle were performed with the image J software and the ratio
Cx43/muscle was analyzed in the left ventricle, interventricular septum and right ventricle. Results: The ratio Cx43/muscle was significantly
reduced in LFN-exposed rats (p=0.001). The mean value decreased 46.2%, 22.2% and 55.6% respectively in the left ventricle (p=0.008),
interventricular septum (p=0.301) and right ventricle (p=0.004). Conclusions: LFN induces modifications on cardiac Cx43 in rats. The Cx43
reduction observed in our study suggests that LFN may induce an arrhythmogenic substrate and opens a new investigational area concerning
the effects of LFN on the heart. (IJCEP1307020).

Keywords: Low-frequency noise, connexin43, gap junction, intercalated disks, ventricular myocardium

Address correspondence to: Eduardo Antunes, CIIEM, Centro de Investigação Interdisciplinar Egas Moniz, Instituto Superior das Ciências da
Saúde Egas Moniz, ISCSEM, Quinta da Granja, Monte de Caparica, 2829-511 Caparica, Portugal. E-mail: ejpantunes@sapo.pt