Document Detail


Roles of nitric oxide, nitrite and myoglobin on myocardial efficiency in trout (Oncorhynchus mykiss) and goldfish (Carassius auratus): implications for hypoxia tolerance.
MedLine Citation:
PMID:  20675545     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The roles of nitric oxide synthase activity (NOS), nitrite and myoglobin (Mb) in the regulation of myocardial function during hypoxia were examined in trout and goldfish, a hypoxia-intolerant and hypoxia-tolerant species, respectively. We measured the effect of NOS inhibition, adrenaline and nitrite on the O(2) consumption rate and isometric twitch force development in electrically paced ventricular preparations during hypoxia, and measured O(2) affinity and nitrite reductase activity of the purified heart Mbs of both species. Upon hypoxia (9% O(2)), O(2) consumption and developed force decreased in both trout and goldfish myocardium, with trout showing a significant increase in the O(2) utilization efficiency, i.e. the ratio of twitch force to O(2) consumption, suggesting an increased anaerobic metabolism. NOS inhibition enhanced myocardial O(2) consumption and decreased efficiency, indicating that mitochondrial respiration is under a tone of NOS-produced NO. When trout myocardial twitch force and O(2) consumption are enhanced by adrenaline, this NO tone disappears. Consistent with its conversion to NO, nitrite reduced O(2) consumption and increased myocardial efficiency in trout but not in goldfish. Such a difference correlates with the lower O(2) affinity measured for trout Mb that would increase the fraction of deoxygenated heme available to catalyze the reduction of nitrite to NO. Whereas low-affinity trout Mb would favor O(2) diffusion within cardiomyocytes at high in vivo O(2) tensions, goldfish Mb having higher O(2) affinity and higher nitrite reductase activity appears better suited to facilitate O(2) diffusion and nitrite reduction in the heart during severe hypoxia, a condition particularly well tolerated by this species.
Authors:
Claus Lunde Pedersen; Serena Faggiano; Signe Helbo; Hans Gesser; Angela Fago
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  213     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-02     Completed Date:  2010-11-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2755-62     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, Universitetsparken, Aarhus University, DK-8000, Aarhus C, Denmark.
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MeSH Terms
Descriptor/Qualifier:
Animals
Anoxia / metabolism*
Goldfish / metabolism*
Myocardial Contraction / physiology
Myocardium / metabolism*
Myoglobin / metabolism*
Nitric Oxide / metabolism*
Nitric Oxide Synthase / metabolism
Nitrites / metabolism*
Oncorhynchus mykiss / metabolism*
Oxygen Consumption / physiology
Chemical
Reg. No./Substance:
0/Myoglobin; 0/Nitrites; 10102-43-9/Nitric Oxide; EC 1.14.13.39/Nitric Oxide Synthase

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


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