• myGriffith
    • Staff portal
    • Contact Us⌄
      • Future student enquiries 1800 677 728
      • Current student enquiries 1800 154 055
      • International enquiries +61 7 3735 6425
      • General enquiries 07 3735 7111
      • Online enquiries
      • Staff phonebook
    View Item 
    •   Home
    • Griffith Research Online
    • Journal articles
    • View Item
    • Home
    • Griffith Research Online
    • Journal articles
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

  • All of Griffith Research Online
    • Communities & Collections
    • Authors
    • By Issue Date
    • Titles
  • This Collection
    • Authors
    • By Issue Date
    • Titles
  • Statistics

  • Most Popular Items
  • Statistics by Country
  • Most Popular Authors
  • Support

  • Contact us
  • FAQs
  • Admin login

  • Login
  • Hypoxia tolerance in elasmobranchs. I. Critical oxygen tension as a measure of blood oxygen transport during hypoxia exposure

    Author(s)
    Speers-Roesch, B
    Richards, JG
    Brauner, CJ
    Farrell, AP
    Hickey, AJR
    Wang, YS
    Renshaw, GMC
    Griffith University Author(s)
    Renshaw, Gillian M.
    Year published
    2012
    Metadata
    Show full item record
    Abstract
    The critical O2 tension of whole-animal O2 consumption rate (Embedded Image), or Pcrit, is the water PO2 (PwO2) at which an animal transitions from an oxyregulator to an oxyconformer. Although Pcrit is a popular measure of hypoxia tolerance in fishes because it reflects the capacity for O2 uptake from the environment at low PwO2, little is known about the interrelationships between Pcrit and blood O2 transport characteristics and increased use of anaerobic metabolism during hypoxia exposure in fishes, especially elasmobranchs. We addressed this knowledge gap using progressive hypoxia exposures of two elasmobranch species ...
    View more >
    The critical O2 tension of whole-animal O2 consumption rate (Embedded Image), or Pcrit, is the water PO2 (PwO2) at which an animal transitions from an oxyregulator to an oxyconformer. Although Pcrit is a popular measure of hypoxia tolerance in fishes because it reflects the capacity for O2 uptake from the environment at low PwO2, little is known about the interrelationships between Pcrit and blood O2 transport characteristics and increased use of anaerobic metabolism during hypoxia exposure in fishes, especially elasmobranchs. We addressed this knowledge gap using progressive hypoxia exposures of two elasmobranch species with differing hypoxia tolerance. The Pcrit of the hypoxia-tolerant epaulette shark (Hemiscyllium ocellatum, 5.10±0.37 kPa) was significantly lower than that of the comparatively hypoxia-sensitive shovelnose ray (Aptychotrema rostrata, 7.23±0.40 kPa). Plasma [lactate] was elevated above normoxic values at around Pcrit in epaulette sharks, but increased relative to normoxic values at PwO2 below Pcrit in shovelnose rays, providing equivocal support for the hypothesis that Pcrit is associated with increased anaerobic metabolism. The Embedded Image, arterial PO2 and arterial blood O2 content (CaO2) were similar between the two species under normoxia and decreased in both species with progressive hypoxia, but as PwO2 declined, epaulette sharks had a consistently higher Embedded Image and CaO2 than shovelnose rays, probably due to their significantly greater in vivo haemoglobin (Hb)–O2 binding affinity (in vivo Hb–O2 P50=4.27±0.57 kPa for epaulette sharks vs 6.35±0.34 kPa for shovelnose rays). However, at PwO2 values representing the same percentage of each species' Pcrit (up to ∼175% of Pcrit), Hb–O2 saturation and CaO2 were similar between species. These data support the hypothesis that Hb–O2 P50 is an important determinant of Pcrit and suggest that Pcrit can predict Hb–O2 saturation and CaO2 during hypoxia exposure, with a lower Pcrit being associated with greater O2 supply at a given PwO2 and consequently better hypoxia tolerance. Thus, Pcrit is a valuable predictor of environmental hypoxia tolerance and hypoxia exposures standardized at a given percentage of Pcrit will yield comparable levels of arterial hypoxaemia, facilitating cross-species comparisons of responses to hypoxia.
    View less >
    Journal Title
    Journal of Experimental Biology
    Volume
    215
    Issue
    1
    DOI
    https://doi.org/10.1242/jeb.059642
    Copyright Statement
    Self-archiving of the author-manuscript version is not yet supported by this journal. Please refer to the journal link for access to the definitive, published version or contact the authors for more information.
    Subject
    Biological sciences
    Other biological sciences not elsewhere classified
    Biomedical and clinical sciences
    Publication URI
    http://hdl.handle.net/10072/47573
    Collection
    • Journal articles

    Footer

    Disclaimer

    • Privacy policy
    • Copyright matters
    • CRICOS Provider - 00233E
    • TEQSA: PRV12076

    Tagline

    • Gold Coast
    • Logan
    • Brisbane - Queensland, Australia
    First Peoples of Australia
    • Aboriginal
    • Torres Strait Islander