| The role of adrenergic stimulation in maintaining maximum cardiac performance in rainbow trout (Oncorhynchus mykiss) during hypoxia, hyperkalemia and acidosis at 10 degrees C. | |
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MedLine Citation:
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PMID: 16788027 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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As rainbow trout approach exhaustion during prolonged exercise, they maintain maximum cardiac output despite the fact their venous blood, which bathes the heart, becomes hypoxic, acidotic and hyperkalemic. Because these factors are individually recognized to have detrimental inotropic and chronotropic effects on cardiac performance, we hypothesized that adrenergic stimulation is critical in maintaining maximum cardiac performance under these collectively adverse conditions in vivo. To test this hypothesis, maximum cardiac performance in the presence and absence of maximal adrenergic stimulation was assessed with in situ rainbow trout hearts using relevant hyperkalemic (5.0 mmol l(-1) K+), acidotic (pH 7.5) and hypoxic challenges. With tonic adrenergic stimulation (5.0 nmol l(-1) adrenaline), hearts produced only 44.8+/-14.6% of their normal maximum cardiac output when exposed under normoxic conditions (20 kPa) to the hyperkalemic, acidotic perfusate, indicating that in vivo there was no refuge from cardiac impairment even if venous blood was fully oxygenated. By contrast, maximum adrenergic stimulation (500 nmol l(-1) adrenaline), fully protected maximum cardiac performance under hyperkalemic and acidotic conditions over a wide range of oxygen availability, from normoxia to 2.0 kPa, a venous oxygen tension close to routine values in vivo. Extending the level of hypoxia to 1.3 kPa resulted in a 43.6+/-2.8% decrease in maximum cardiac output, with hearts failing when tested at 1.0 kPa. Our results suggest that adrenergic stimulation of the trout heart is critical in maintaining maximum performance during prolonged swimming tests, and probably during all forms of exhaustive activity and recovery, when venous blood is hyperkalemic, acidotic and hypoxic. |
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Authors:
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Linda M Hanson; Shannon Obradovich; Janet Mouniargi; Anthony P Farrell |
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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: 209 ISSN: 0022-0949 ISO Abbreviation: J. Exp. Biol. Publication Date: 2006 Jul |
Date Detail:
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Created Date: 2006-06-21 Completed Date: 2006-09-01 Revised Date: 2008-11-21 |
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: 2442-51 Citation Subset: IM |
Affiliation:
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Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada. hanson@zoology.ubc.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acidosis
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physiopathology,
veterinary* Adrenergic Agonists / pharmacology Animals Anoxia / physiopathology, veterinary* Cardiac Output* / drug effects Catecholamines / metabolism Epinephrine / pharmacology* Female Fish Diseases / blood, physiopathology* Heart / drug effects Hydrogen-Ion Concentration Hyperkalemia / physiopathology, veterinary* Male Oncorhynchus mykiss / blood, physiology* Oxygen / blood Perfusion Physical Exertion / physiology Potassium / blood Temperature |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic Agonists; 0/Catecholamines; 51-43-4/Epinephrine; 7440-09-7/Potassium; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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