Ionic regulation and Na(+)-K(+)-ATPase activity in gills and kidney of the freshwater stingray Paratrygon aiereba living in white and blackwaters in the Amazon Basin.
During low-water period, freshwater stingray Paratrygon aiereba collected in the whitewater (WW) of the River Amazon showed higher urea content, osmolality, Na(+) and Cl(-) concentrations in plasma and perivisceral fluid than those caught in blackwater (BW) of the River Negro. Gills and kidney Na(+)-K(+)-ATPase activities were significantly lower in WW than in BW fish. The high level of kidney Na(+)-K(+)-ATPase activity in P. aiereba may minimize ion loss and generate diluted solute-free urine in ion-poor BW environment.
Duncan
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WP
Departamento de Morfologia, Universidade Federal do Amazonas, Avenida General Rodrigo Octávio Jordão Ramos, 3000. Coroado I, Manaus, AM, Brazil. wduncan@ufam.edu.br
Costa
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Araújo
M L G
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Fernandes
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MN
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis; D005880:Gills / Q000201:enzymology*; D007668:Kidney / Q000201:enzymology*; D045483:Rivers; D012860:Skates, Fish / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014508:Urea / Q000097:blood; D014882:Water-Electrolyte Balance / Q000502:physiology*
D001786:Blood Glucose; D001798:Blood Proteins; D014508:Urea; D000254:Sodium-Potassium-Exchanging ATPase