Specialized impulse conduction pathway in the alligator heart
- Academic Medical Center, University of Amsterdam, Netherlands
- University of North Texas, United States
- George Washington University, United States
- Rockefeller Wildlife Refuge, United States
- Charles University, Czech Republic
Abstract
Mammals and birds have a specialized cardiac atrioventricular conduction system enabling rapid activation of both ventricles. This system may have evolved together with high heart rates to support their endothermic state (warm-bloodedness), and is seemingly lacking in ectothermic vertebrates from which first mammals then birds independently evolved. Here, we studied the conduction system in crocodiles (Alligator mississippiensis), the only ectothermic vertebrates with a full ventricular septum. We identified homologues of mammalian conduction system markers (Tbx3-Tbx5, Scn5a, Gja5, Nppa-Nppb) and show the presence of a functional atrioventricular bundle. The ventricular Purkinje network, however, was absent and slow ventricular conduction relied on trabecular myocardium, as it does in other ectothermic vertebrates. We propose the evolution of the atrioventricular bundle followed full ventricular septum formation prior to the development of high heart rates and endothermy. In contrast, the evolution of the ventricular Purkinje network is strongly associated with high heart rates and endothermy.
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Author details
Vincent M Christoffels
Funding
Carlsbergfondet
- Bjarke Jensen
Fondation Leducq
- Vincent M Christoffels
CVON HUSTCARE
- Vincent M Christoffels
Netherlands Heart Foundation (COBRA3)
- Vincent M Christoffels
Netherlands Heart Foundation (2016T047)
- Bastiaan JD Boukens
CVON2014-2018 (CONCOR-genes)
- Alex V Postma
CVON2014-2018 (CONCOR-genes)
- Vincent M Christoffels
Czech Science Foundation (16-02972S)
- David Sedmera
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: The investigation conforms with the guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No. 8523, revised 1996) and was approved by the Institutional Animal Studies Care and Use Committee of the University of North Texas (IACUC #1403-04).
Copyright
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
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Specialized impulse conduction pathway in the alligator heart
eLife 7:e32120.
https://doi.org/10.7554/eLife.32120
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