Effects of chronic atrial fibrillation on gap junction distribution in human and rat atria
Lioudmila Polontchouk, PhD*,
Jacques-Antoine Haefliger, PhD ,
Berit Ebelt*,
Thomas Schaefer, PhD ,
Dominik Stuhlmann, MSc,
Uwe Mehlhorn, MD ,
Ferdinand Kuhn-Regnier, MD,
E. Rainer De Vivie, MD, PhD and
Stefan Dhein, MD, PhD*
* Department of Pharmacology, Martin Luther University of Halle-Wittenberg, Halle/S, Germany
Department of Internal Medicine B, Laboratory of Molecular Biology, Centre Hospitalier Universitaire Vañdias Lausanne, Lausanne, Switzerland
Department of Pharmacology, University of Cologne, Cologne, Germany
Clinic of Cardiothoracic Surgery, University of Cologne, Cologne, Germany
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Figure 1 Scheme of the cell sections as used for the analysis. For description, see text.
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Figure 2 Atrial fibrillation (AF) and the connexin expression. (A) Western blots of human atrial tissue lysates with monoclonal antibody raised against residues 252–271 of rat connexin43. A specific band migrating at 45 kDa is detected in the lysates prepared from atria of patients with sinus rhythm (SR) and with atrial fibrillation (AF). (B) Western blots of cardiac lysates with anti-connexin40 antibody. The antibody recognized a single band migrating at 40 kDa in lysates prepared from atria of patients with SR and with AF.
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Figure 3 Atrial fibrillation alters the membrane distribution of connexins. Immunostaining for connexin43 (Cx43) (A,B) and connexin40 (Cx40) (C,D) in atrial tissue from patients with sinus rhythm (upper parts) and from patients with chronic atrial fibrillation (lower parts). The specific connexin signals either for Cx43 or for Cx40 are shown in green. The red arrows indicate the immunopositive cell poles, whereas the light blue arrows point to the lateral immunostaining. Diagrammatic representations of the corresponding tissue sections are shown on the right side. The yellowish stainings indicate deposition of lipofuscin, which is typical for human atrial tissue of adult or aged patients.
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Figure 4 Original recordings of transmembrane action potentials measured with 15-M sharp glass microelectrodes (filled with 3 mol/l KCl) from rat atrium before, during (10 h of rapid pacing) and after the end of 24 h of 10-Hz stimulation. The traces are photographically reproduced from the original oscilloscope signals.
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Figure 5 Effect of the induced atrial fibrillation on the connexin43 (Cx43) distribution in the membrane of rat atrial cardiomyocytes. Ratio of the membrane length positively stained (PLM) for Cx43 as referred to the total membrane length (LM) of the polar membrane and of the lateral membrane. The results are represented as mean ± SEM of 600 cells per experimental group. Significant difference between the staining of the polar membrane and the lateral membrane is indicated by an asterisk; significant difference against the directly frozen control group is indicated by the pound symbol (#) (level of significance p < 0.05).
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Figure 6 Atrial fibrillation increases the transverse conduction velocity in isolated rat atria. Original traces showing the stimulus and the response for transverse and longitudinal conduction are given. Ratios of the longitudinal and transverse conduction velocities (VL/VT) measured after 24 h in the bath (at the spontaneous beating rate) and after 24 h atrial fibrillation are given as mean ± SEM in the upper panel. The difference was significant (p < 0.05).
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