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Limited extracellular but complete intracellular acid-base regulation during short-term environmental hypercapnia in the armoured catfish, Liposarcus pardalis.
Brauner, C J; Wang, T; Wang, Y; Richards, J G; Gonzalez, R J; Bernier, N J; Xi, W; Patrick, M; Val, A L.
Afiliación
  • Brauner CJ; Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, B.C., Canada. brauner@zoology.ubc.ca
J Exp Biol ; 207(Pt 19): 3381-90, 2004 Sep.
Article en En | MEDLINE | ID: mdl-15326214
ABSTRACT
Environmental hypercapnia induces a respiratory acidosis that is usually compensated within 24-96 h in freshwater fish. Water ionic composition has a large influence on both the rate and degree of pH recovery during hypercapnia. Waters of the Amazon are characteristically dilute in ions, which may have consequences for acid-base regulation during environmental hypercapnia in endemic fishes. The armoured catfish Liposarcus pardalis, from the Amazon, was exposed to a water P(CO(2)) of 7, 14 or 42 mmHg in soft water (in micromol l(-1) Na(+), 15, Cl(-), 16, K(+), 9, Ca(2+), 9, Mg(2+), 2). Blood pH fell within 2 h from a normocapnic value of 7.90+/-0.03 to 7.56+/-0.04, 7.34+/-0.05 and 6.99+/-0.02, respectively. Only minor extracellular pH (pH(e)) recovery was observed in the subsequent 24-96 h. Despite the pronounced extracellular acidosis, intracellular pH (pH(i)) of the heart, liver and white muscle was tightly regulated within 6 h (the earliest time at which these parameters were measured) via a rapid accumulation of intracellular HCO(3)(-). While most fish regulate pH(i) during exposure to environmental hypercapnia, the time course for this is usually similar to that for pH(e) regulation. The degree of extracellular acidosis tolerated by L. pardalis, and the ability to regulate pH(i) in the face of an extracellular acidosis, are the greatest reported to date in a teleost fish. The preferential regulation of pH(i) in the face of a largely uncompensated extracellular acidosis in L. pardalis is rare among vertebrates, and it is not known whether this is associated with the ability to air-breathe and tolerate aerial exposure, or living in water dilute in counter ions, or with other environmental or evolutionary selective pressures. The ubiquity of this strategy among Amazonian fishes and the mechanisms employed by L. pardalis are clearly worthy of further study.
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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Equilibrio Ácido-Base / Acidosis Respiratoria / Bagres / Dióxido de Carbono Límite: Animals País/Región como asunto: America do sul / Brasil Idioma: En Revista: J Exp Biol Año: 2004 Tipo del documento: Article País de afiliación: Canadá Pais de publicación: ENGLAND / ESCOCIA / GB / GREAT BRITAIN / INGLATERRA / REINO UNIDO / SCOTLAND / UK / UNITED KINGDOM
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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Equilibrio Ácido-Base / Acidosis Respiratoria / Bagres / Dióxido de Carbono Límite: Animals País/Región como asunto: America do sul / Brasil Idioma: En Revista: J Exp Biol Año: 2004 Tipo del documento: Article País de afiliación: Canadá Pais de publicación: ENGLAND / ESCOCIA / GB / GREAT BRITAIN / INGLATERRA / REINO UNIDO / SCOTLAND / UK / UNITED KINGDOM