| Ammonia as a respiratory gas in water and air-breathing fishes. | |
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MedLine Citation:
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PMID: 16731054 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Ammonia is produced in the liver and excreted as NH(3) by diffusion across the gills. Elevated ammonia results in an increase in gill ventilation, perhaps via stimulation of gill oxygen chemo-receptors. Acidification of the water around the fish by carbon dioxide and acid excretion enhances ammonia excretion and constitutes "environmental ammonia detoxification". Fish have difficulties in excreting ammonia in alkaline water or high concentrations of environmental ammonia, or when out of water. The mudskipper, Periphthalmodon schlosseri, is capable of active NH(4)(+) transport, maintaining low internal levels of ammonia. To prevent a back flux of NH(3), these air-breathing fish can increase gill acid excretion and reduce the membrane NH(3) permeability by modifying the phospholipid and cholesterol compositions of their skin. Several air-breathing fish species can excrete ammonia into air through NH(3) volatilization. Some fish detoxify ammonia to glutamine or urea. The brains of some fish can tolerate much higher levels of ammonia than other animals. Studies of these fish may offer insights into the nature of ammonia toxicity in general. |
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Authors:
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David J Randall; Yuen K Ip |
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Publication Detail:
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Type: Journal Article; Review Date: 2006-04-25 |
Journal Detail:
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Title: Respiratory physiology & neurobiology Volume: 154 ISSN: 1569-9048 ISO Abbreviation: Respir Physiol Neurobiol Publication Date: 2006 Nov |
Date Detail:
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Created Date: 2006-11-06 Completed Date: 2007-02-20 Revised Date: 2008-11-21 |
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: 216-25 Citation Subset: IM |
Affiliation:
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Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Hong Kong, China. BHRAND@cityu.edu.hk |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adaptation, Physiological Air* Ammonia / metabolism* Animals Fishes / physiology* Gills / physiology Hydrogen-Ion Concentration Ion Transport / physiology Respiration* Respiratory Physiological Phenomena* Water |
| Chemical | |
Reg. No./Substance:
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7664-41-7/Ammonia; 7732-18-5/Water |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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