Enzymatic and mitochondrial responses to 5 months of aerial exposure in the slender lungfish Protopterus dolloi

J. F. Staples, M. Kajimura, C. M. Wood, M. Patel, Y. K. Ip, G. B. McClelland

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Mitochondrial respiration and activities of key metabolic enzymes from liver and white skeletal muscle were compared between control aquatic slender lungfish Protopterus dolloi, and those exposed to air for 5 months. Activities of citrate synthase, glycogen phosphorylase, phosphofructokinase and pyruvate kinase in liver were not affected by air-exposure. In muscle, air-exposure reduced citrate synthase and pyruvate kinase activities (relative to tissue wet mass) by 63 and 50%, respectively. Liver carnitine palmitoyl transferase activity (relative to mitochondrial protein) decreased by half following air-exposure, but there was no change in muscle. In mitochondria isolated from muscle, state 3 and state 4 respiration were reduced by 74 and 89%, respectively following air-exposure, but liver mitochondria were not affected. In liver, air-exposure increased activities of ornithine-urea cycle enzymes including glutamine synthase, carbamoyl-phosphate synthase III and arginase, by 1.9- to 4.2-fold. Carbamoyl-phosphate synthase III activity could not be detected in muscle, indicating that urea is not synthesized in this tissue. These data suggest that skeletal muscle metabolism is downregulated in air-exposure, conserving energy and protein during a period when the animals cannot forage. In contrast, ATP production capacities in the liver are maintained, and this may permit expensive urea biosynthesis to continue during aerial exposure.

Original languageEnglish
Pages (from-to)608-622
Number of pages15
JournalJournal of Fish Biology
Volume73
Issue number3
DOIs
StatePublished - Aug 1 2008

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air exposure
muscle
air
liver
urea
muscles
mitochondrion
pyruvate kinase
citrate (si)-synthase
respiration
breathing
skeletal muscle
phosphate
enzyme
mitochondria
urea cycle enzymes
phosphates
protein
carnitine palmitoyltransferase
arginase

Keywords

  • Aestivation
  • Dipnoi
  • Glycolysis
  • Ornithine-urea cycle
  • Oxidative phosphorylation

ASJC Scopus subject areas

  • Aquatic Science

Cite this

Enzymatic and mitochondrial responses to 5 months of aerial exposure in the slender lungfish Protopterus dolloi. / Staples, J. F.; Kajimura, M.; Wood, C. M.; Patel, M.; Ip, Y. K.; McClelland, G. B.

In: Journal of Fish Biology, Vol. 73, No. 3, 01.08.2008, p. 608-622.

Research output: Contribution to journalArticle

Staples, J. F. ; Kajimura, M. ; Wood, C. M. ; Patel, M. ; Ip, Y. K. ; McClelland, G. B. / Enzymatic and mitochondrial responses to 5 months of aerial exposure in the slender lungfish Protopterus dolloi. In: Journal of Fish Biology. 2008 ; Vol. 73, No. 3. pp. 608-622.
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