Document Detail

Compensation for hypercapnia by a euryhaline elasmobranch: effect of salinity and roles of gills and kidneys in fresh water.
MedLine Citation:
PMID:  12911113     Owner:  NLM     Status:  MEDLINE    
Specimens of the euryhaline elasmobranch, Dasyatis sabina were acclimated to seawater and fresh water, and exposed to normocapnic (air) and hypercapnic (1% CO2 in air) environmental water. Blood pH, PCO2, and [HCO3-], as well as whole-animal net-acid excretion, were measured for up to 24 h of hypercapnia. In a separate experimental series, urine was collected from freshwater acclimated stingrays during 8 h of normocapnia and hypercapnia. Stingrays in both salinities at least partially compensated for the respiratory acidosis by accumulating HCO3- in their extracellular spaces. The degree of compensation for blood pH was 88.5% in seawater, but only 31.0% in fresh water after 24 h of hypercapnia. Whole-animal net-acid excretion was also greater in seawater than in fresh water, as was the increase in extracellular fluid [HCO3-]. Mean urinary net-acid excretion rates were slightly negative, and never increased above normocapnic control rates during hypercapnia. Since whole-animal net-acid excretion rates increased with blood [HCO3-], and urinary excretion was always negative, the gills were probably the primary organ responsible for compensation from environmental hypercapnia. The faster, and more complete, compensation for hypercapnia in seawater than in fresh water for this euryhaline elasmobranch is consistent with data for euryhaline teleosts, and probably reflects Na+-dependent mechanisms of branchial acid excretion.
Keith Patrick Choe; David H Evans
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of experimental zoology. Part A, Comparative experimental biology     Volume:  297     ISSN:  1548-8969     ISO Abbreviation:  J. Exp. Zoolog. Part A Comp. Exp. Biol.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-08-12     Completed Date:  2003-12-23     Revised Date:  2009-10-05    
Medline Journal Info:
Nlm Unique ID:  101168223     Medline TA:  J Exp Zool A Comp Exp Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  52-63     Citation Subset:  IM    
Department of Zoology, University of Florida, Gainesville, Florida 32611, USA.
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MeSH Terms
Bicarbonates / blood,  urine
Carbon Dioxide / pharmacology
Fresh Water / chemistry*
Gills / drug effects*,  physiology
Hydrogen-Ion Concentration
Hypercapnia / blood,  physiopathology*,  urine
Kidney / drug effects*,  physiology
Skates (Fish) / blood,  physiology*,  urine
Sodium Chloride / pharmacology*
Reg. No./Substance:
0/Bicarbonates; 124-38-9/Carbon Dioxide; 7647-14-5/Sodium Chloride

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