| Tribute to P. L. Lutz: cardiac performance and cardiovascular regulation during anoxia/hypoxia in freshwater turtles. | |
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MedLine Citation:
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PMID: 17488932 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Freshwater turtles overwintering in ice-covered ponds in North America may be exposed to prolonged anoxia, and survive this hostile environment by metabolic depression. Here, we review their cardiovascular function and regulation, with particular emphasis on the factors limiting cardiac performance. The pronounced anoxia tolerance of the turtle heart is based on the ability to match energy consumption with the low anaerobic ATP production during anoxia. Together with a well-developed temporal and spatial energy buffering by creatine kinase, this allows for cellular energy charge to remain high during anoxia. Furthermore, the turtle heart is well adapted to handle the adverse effects of free phosphate arising when phosphocreatine stores are used. Anoxia causes tenfold reductions in heart rate and blood flows that match the metabolic depression, and blood pressure is largely maintained through increased systemic vascular resistance. Depression of the heart rate is not driven by the autonomic nervous system and seems to arise from direct effects of oxygen lack and the associated hyperkalaemia and acidosis on the cardiac pacemaker. These intra- and extracellular changes also affect cardiac contractility, and both acidosis and hyperkalaemia severely depress cardiac contractility. However, increased levels of adrenaline and calcium may, at least partially, salvage cardiac function under prolonged periods of anoxia. |
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Authors:
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Johannes Overgaard; Hans Gesser; Tobias Wang |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Review |
Journal Detail:
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Title: The Journal of experimental biology Volume: 210 ISSN: 0022-0949 ISO Abbreviation: J. Exp. Biol. Publication Date: 2007 May |
Date Detail:
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Created Date: 2007-05-09 Completed Date: 2008-01-17 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0243705 Medline TA: J Exp Biol Country: England |
Other Details:
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Languages: eng Pagination: 1687-99 Citation Subset: IM |
Affiliation:
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National Environmental Research Institute, Aarhus University, Silkeborg, Denmark. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adaptation, Physiological
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physiology* Adenosine Triphosphate / metabolism Animals Anoxia / physiopathology* Creatine Kinase / metabolism Energy Metabolism / physiology* Heart / physiology* Heart Rate / physiology Myocardial Contraction / physiology North America Phosphates / metabolism Regional Blood Flow / physiology Turtles / physiology* |
| Chemical | |
Reg. No./Substance:
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0/Phosphates; 56-65-5/Adenosine Triphosphate; EC 2.7.3.2/Creatine Kinase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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