Document Detail

Carbohydrate and amino acid metabolism in fasting and aestivating African lungfish (Protopterus dolloi).
MedLine Citation:
PMID:  18593602     Owner:  NLM     Status:  MEDLINE    
The potential importance of carbohydrates and amino acids as fuels during periods of fasting and aestivation in the African lungfish, Protopterus dolloi, were examined. No significant decreases in tissue glycogen levels were observed following 60 days of fasting or aestivation, suggesting lungfish may undergo 'glycogen sparing'. Yet glycogenolysis may be important during aestivation based on the differing responses of two flux-generating enzymes of the glycolytic pathway, hexokinase (HK) and pyruvate kinase (PK). PK is required for glycogen breakdown whereas HK is not. HK activity is significantly down-regulated in the heart and gill tissues during aestivation, while PK activity is sustained. The significant negative correlation between the activity of HK and glucose levels in the heart of aestivating lungfish suggests HK may be regulated by glucose concentrations. There was no indication of anaerobic glycolytic flux during aestivation as lactate did not accumulate in any of the tissues examined, and no significant induction of lactate dehydrogenase (LDH)activity was observed. The increase in glutamate dehydrogenase (GDH) and aspartate aminotransferase (Asp-AT) activities in the liver of aestivating P. dolloi suggests some energy may be obtained via increased aminoacid catabolism, leading to the generation of tricarboxylic acid (TCA) cycle intermediates. These findings indicate the importance of both carbohydrate and amino acid fuel stores during aestivation in aphylogenetically ancient, air-breathing fish.
Natasha Therese Frick; Jason Scott Bystriansky; Yuen Kwong Ip; Shit Fun Chew; James Stuart Ballantyne
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-06-14
Journal Detail:
Title:  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology     Volume:  151     ISSN:  1531-4332     ISO Abbreviation:  Comp. Biochem. Physiol., Part A Mol. Integr. Physiol.     Publication Date:  2008 Sep 
Date Detail:
Created Date:  2008-08-04     Completed Date:  2008-09-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9806096     Medline TA:  Comp Biochem Physiol A Mol Integr Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  85-92     Citation Subset:  IM    
Department of Integrative Biology, University of Guelph, Guelph, Ont. N1G2W1, Canada.
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MeSH Terms
Amino Acids / metabolism*
Blood Glucose / metabolism
Carbohydrate Metabolism*
Citrate (si)-Synthase / metabolism
Estivation / physiology*
Fasting / physiology*
Fishes / physiology*
Glycogen / blood
Hexokinase / metabolism
L-Lactate Dehydrogenase / metabolism
Lactic Acid / blood
Muscles / metabolism
Myocardium / enzymology
Osmolar Concentration
Water / metabolism
Reg. No./Substance:
0/Amino Acids; 0/Blood Glucose; 50-21-5/Lactic Acid; 7732-18-5/Water; 9005-79-2/Glycogen; EC Dehydrogenase; EC (si)-Synthase; EC

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