Document Detail

Oxygen transport capacity in the air-breathing fish, Megalops cyprinoides: compensations for strenuous exercise.
MedLine Citation:
PMID:  12507606     Owner:  NLM     Status:  MEDLINE    
Tarpon have high resting or routine hematocrits (Hct) (37.6+/-3.4%) and hemoglobin concentrations (120.6+/-7.3 gl(-1)) that increased significantly following bouts of angling-induced exercise (51.9+/-3.7% and 142.8+/-13.5 gl(-1), respectively). Strenuous exercise was accompanied by an approximately tenfold increase in blood lactate and a muscle metabolite profile indicative of a high energy demand teleost. Routine blood values were quickly restored only when this facultative air-breathing fish was given access to atmospheric air. In vitro studies of oxygen transport capacity, a function of carrying capacity and viscosity, revealed that the optimal Hct range corresponded to that observed in fish under routine behaviour. During strenuous exercise however, further increase in viscosity was largely offset by a pronounced reduction in the shear-dependence of blood which conformed closely to an ideal Newtonian fluid. The mechanism for this behaviour of the erythrocytes appears to involve the activation of surface adrenergic receptors because pre-treatment with propranolol abolished the response. High levels of activity in tarpon living in hypoxic habitats are therefore supported by an elevated Hct with adrenergically mediated viscosity reduction, and air-breathing behaviour that enables rapid metabolic recovery.
R M G Wells; J Baldwin; R S Seymour; R V Baudinette; K Christian; M B Bennett
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology     Volume:  134     ISSN:  1095-6433     ISO Abbreviation:  Comp. Biochem. Physiol., Part A Mol. Integr. Physiol.     Publication Date:  2003 Jan 
Date Detail:
Created Date:  2002-12-31     Completed Date:  2003-07-24     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9806096     Medline TA:  Comp Biochem Physiol A Mol Integr Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  45-53     Citation Subset:  IM    
School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
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MeSH Terms
Adaptation, Physiological / physiology*
Adenosine Triphosphate / metabolism
Blood Viscosity / physiology
Erythrocytes / metabolism
Fishes / physiology*
Oxygen / metabolism*
Physical Exertion / physiology*
Stress, Physiological / physiopathology
Reg. No./Substance:
0/Hemoglobins; 56-65-5/Adenosine Triphosphate; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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