Hypoxia enhances blood O 2 affinity and depresses skeletal muscle O 2 consumption in zebrafish (Danio rerio)

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Zebrafish (Danio rerio)are widely used animal models. Nevertheless, the mechanisms underlying hypoxia tolerance in this species have remained poorly understood. In the present study, we have determined the effects of hypoxia on blood-O 2 transport properties and mitochondrial respiration rate in permeabilized muscle fibres of adult zebrafish exposed to either 1)a gradual decrease in O 2 levels until fish lost equilibrium (~1 h, acute hypoxia), or 2)severe hypoxia (PO 2 ∼ 15 Torr)for 48 h (prolonged hypoxia). Acute, short-term hypoxia caused an increase in hemoglobin (Hb)O 2 affinity (decrease in P 50 ), due to a decrease in erythrocyte ATP after erythrocyte swelling. No changes in isoHb expression patterns were observed between hypoxic and normoxic treatments. Prolonged hypoxia elicited additional reponses on O 2 consumption: lactate accumulated in the blood, indicating that zebrafish relied on glycolysis for ATP production, and mitochondrial respiration of skeletal muscle was overall significantly inhibited. In addition, male zebrafish had higher hypoxia tolerance (measured as time to loss of equilibrium)than females. The present study contributes to our understanding of the adaptive mechanisms that allow zebrafish, and by inference other fish species, to cope with low O 2 levels.

Original languageEnglish
JournalComparative Biochemistry and Physiology Part - B: Biochemistry and Molecular Biology
Pages (from-to)18-25
Number of pages8
Publication statusPublished - 2019

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