Acid-base regulation during exposure to elevated environmental CO₂ in an osmoconformer, the Pacific Hagfish (Eptatretus stoutii)

Baker, D., Rummer, J., Sardella, B., and Brauner, C. (2006) Acid-base regulation during exposure to elevated environmental CO₂ in an osmoconformer, the Pacific Hagfish (Eptatretus stoutii). Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology, 143 (Suppl 4). S74-S74.

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The ancient hagfish is an osmoconformer, with possibly the most unique blood ionic composition of all craniates. It is known to partially regulate levels of some divalent cations in the blood (ie Ca²⁺ and Mg²⁺), but Na⁺ and Cl⁻ levels in particular are very similar to seawater. Acid-base disturbances in fish are usually corrected through acid-base relevant ion transfer at the gills (ie Na⁺/H⁺ or Cl⁻/HCO⁻₃), ultimately affecting plasma Na⁺ and/or Cl⁻ levels. Based upon the feeding behaviour of hagfish, large metabolic and/or respiratory acidoses are likely experienced: however, nothing is known about this osmoconformer's ability to acid-base regulate, which would require some degree of Na⁺ and/or Cl⁻ regulation. We exposed Pacific Hagfish, Eptatretus stoutii, to three levels of environmental hypercarbia (2%, 6% and 10% CO₂, balance air), and extra- and intracellular acid-base status were monitored up to 96 h of exposure. At all levels of hypercarbia, a pronounced acidosis was observed (e.g., pH_7 at 10% CO₂ in 3 h), but significant compensation occurred within 48 h. Interestingly, [HCO⁻₃] in the blood reached as high as 100 mM, the greatest level of HCO⁻₃ accumulation observed in any vertebrate exposed to short-term hypercarbia. Thus, although the hagfish is a text book example of an osmoconformer, it is one of the most effective vertebrates in dealing with a respiratory acidosis. The ability to accumulate such high levels of HCO⁻₃ is likely associated with the high levels of plasma Cl⁻ and stuff.

Item ID: 45330
Item Type: Article (Abstract)
ISSN: 1531-4332
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Abstract from the Annual Main Meeting of the Society for Experimental Biology, University of Kent at Canterbury, UK, 2nd-7th April, 2006

Date Deposited: 05 Sep 2016 23:23
FoR Codes: 06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060303 Biological Adaptation @ 50%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060309 Phylogeny and Comparative Analysis @ 50%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960301 Climate Change Adaptation Measures @ 50%
96 ENVIRONMENT > 9601 Air Quality > 960104 Marine Air Quality @ 50%
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