| Use it or lose it? Sablefish, Anoplopoma fimbria, a species representing a fifth teleostean group where the betaNHE associated with the red blood cell adrenergic stress response has been secondarily lost. | |
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MedLine Citation:
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PMID: 20400635 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Like most teleosts, sablefish (Anoplopoma fimbria Pallas 1814) blood exhibits a moderate Root effect (~35% maximal desaturation), where a reduction in blood pH dramatically reduces O(2) carrying capacity, a mechanism important for oxygenating the eye and filling the swim bladder (SB) in teleosts. Although sablefish lack a SB, we observed a well-defined choroid rete at the eye. The adrenergically mediated cell swelling typically associated with a functional red blood cell (RBC) beta-adrenergic Na(+)/H(+) exchanger (betaNHE), which would normally protect RBC pH, and thus O(2) transport, during a generalized acidosis, was not observed in sablefish blood. Neither isoproterenol (a beta-agonist) nor 8-bromo cAMP could elicit this response. Furthermore, RBC osmotic shrinkage, known to stimulate NHEs in general and betaNHE in other teleosts such as trout and flounder, resulted in no significant regulatory volume increase (RVI), further supporting the absence of a functional RBC betaNHE. The onset of the Root effect occurs at a much lower RBC pH (6.83-6.92) than in other teleosts, and thus RBC betaNHE may not be required to protect O(2) transport during a generalized acidosis in vivo. Phylogenetically, sablefish may represent a fifth group of teleosts exhibiting a secondary reduction or loss of betaNHE activity. However, sablefish have not lost the choroid rete at the eye (unlike in the other four groups), which may still function with the Root effect to oxygenate the retina, but the low pH onset of the Root effect may ensure haemoglobin (Hb)-O(2) binding is not compromised at the respiratory surface during a general acidosis in the absence of RBC betaNHE. The sablefish may represent an anomaly within the framework of Root effect evolution, in that they possess a moderate Root effect and a choroid rete at the eye, but lack the RBC betaNHE and the SB system. |
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Authors:
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Jodie L Rummer; Mani Roshan-Moniri; Shannon K Balfry; Colin J Brauner |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of experimental biology Volume: 213 ISSN: 1477-9145 ISO Abbreviation: J. Exp. Biol. Publication Date: 2010 May |
Date Detail:
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Created Date: 2010-04-19 Completed Date: 2010-07-05 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: 1503-12 Citation Subset: IM |
Affiliation:
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Department of Zoology, University of British Columbia, No. 2370-6270 University Boulevard, Vancouver, BC, Canada, V6T 1Z4. rummer@zoology.ubc.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic beta-Agonists
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pharmacology Animals Erythrocyte Indices Erythrocytes / cytology, metabolism* Eye / metabolism Fishes / metabolism* Isoproterenol / pharmacology Osmotic Pressure* Oxygen / metabolism* Sodium-Hydrogen Antiporter / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic beta-Agonists; 0/Sodium-Hydrogen Antiporter; 7683-59-2/Isoproterenol; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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