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Cardiac conduction abnormalities in mice lacking the gap junction protein connexin40
S Verheule1, C A van Batenburg, F E Coenjaerts
1Department of Medical Physiology and Sports Medicine, Utrecht University, The Netherlands. sverheul@iupui.edu
Journal of Cardiovascular Electrophysiology
|October 9, 1999
Summary
Connexin40 (Cx40) is crucial for cardiac conduction. Mice lacking Cx40 exhibit impaired atrial conduction and increased susceptibility to atrial tachyarrhythmias, highlighting Cx40's role in heart function.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Electrophysiology
Background:
- Connexin40 (Cx40) is a gap junction protein normally found in the murine atrial myocardium and ventricular conduction system.
- Previous studies noted ECG changes in Cx40-deficient mice, prompting a detailed analysis of cardiac conduction.
Purpose of the Study:
- To investigate the role of Cx40 in cardiac conduction in detail.
- To analyze atrial and ventricular pacing parameters in Cx40 knockout mice.
Main Methods:
- Open-chest, anesthetized mice (Cx40-/- and Cx40+/+) were studied using epicardial electrodes.
- Atrial and ventricular pacing parameters, including sinus node recovery time and Wenckebach period, were measured.
- In vivo conduction velocities were assessed using unipolar recording electrodes.
Main Results:
- Cx40-/- mice showed a significantly longer corrected sinus node recovery time and Wenckebach period compared to wild-type mice.
- Atrial burst pacing induced tachyarrhythmias in 50% of Cx40-/- mice, but none in wild-type mice.
- Atrial conduction velocity was reduced by 30% in Cx40-/- mice, while ventricular conduction velocity remained unchanged.
Conclusions:
- Cx40 plays a significant role in determining conduction properties within the atria and the atrioventricular (AV) conduction system.
- The findings underscore the importance of Cx40 for normal cardiac electrical activity.