| Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus. | |
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MedLine Citation:
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PMID: 18555751 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study determined the respiratory responses to progressive hypoxia in oscar, an extremely hypoxia-tolerant Amazonian cichlid. Oscar depressed oxygen consumption rates (MO2), beginning at a critical O2 tension (Pcrit) of 46Torr, to only 14% of normoxic rates at 10Torr. Total ventilation (Vw) increased up to 4-fold, entirely due to a rise in ventilatory stroke volume (no change in ventilatory frequency), and water convection requirement (Vw/MO2) increased substantially (up to 15-fold). Gill O2 extraction fell steadily, from 60% down to 40%. Although O2 transfer factor (an index of gill O2 diffusion capacity) increased transiently in moderate hypoxia, it decreased at 10Torr, which may have caused the increased expired-arterial PO2 difference. Venous PO2 was always very low (< or =7Torr). Anaerobic metabolism made a significant contribution to ATP supply, indicated by a 3-fold increase in plasma lactate that resulted in an uncompensated metabolic acidosis. Respiration of isolated gill cells was not inhibited until below 5Torr; because gill water PO2 always exceeded this value, hypoxic ion flux arrest in oscars [Wood et al., Am. J. Physiol. Reg. Integr. Comp. Physiol. 292, R2048-R2058, 2007] is probably not caused by O2 limitation in ionocytes. We conclude that metabolic depression and tolerance of anaerobic bi-products, rather than a superior capacity for O2 supply, allow oscar to thrive in extreme hypoxia in the Amazon. |
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Authors:
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Graham R Scott; Chris M Wood; Katherine A Sloman; Fathima I Iftikar; Gudrun De Boeck; Vera M F Almeida-Val; Adalberto L Val |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2008-05-08 |
Journal Detail:
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Title: Respiratory physiology & neurobiology Volume: 162 ISSN: 1569-9048 ISO Abbreviation: Respir Physiol Neurobiol Publication Date: 2008 Jul |
Date Detail:
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Created Date: 2008-07-22 Completed Date: 2008-10-21 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101140022 Medline TA: Respir Physiol Neurobiol Country: Netherlands |
Other Details:
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Languages: eng Pagination: 109-16 Citation Subset: IM |
Affiliation:
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Department of Zoology, University of British Columbia, Vancouver V6T 1Z4, Canada. scott@zoology.ubc.ca |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adaptation, Physiological Anaerobic Threshold / physiology* Animals Anoxia / metabolism* Cell Respiration / physiology Cichlids / physiology* Energy Metabolism / physiology Gills / cytology, physiology Lactic Acid / blood Oxygen Consumption / physiology* Respiratory Mechanics / physiology* |
| Chemical | |
Reg. No./Substance:
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50-21-5/Lactic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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