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|Title:||A protective effect of dietary calcium against acute waterborne cadmium uptake in rainbow trout|
Kamunde, Collins N.
Matsuo, Aline Y.O.
Wood, Chris M.
|metadata.dc.relation.ispartof:||Volume 67, Número 1, Pags. 57-73|
|Abstract:||The present study examined the interactions between elevated dietary calcium (as ionic Ca2+ in the form of CaCl2·2H 2O) and acute waterborne Cd exposure (50μg/l as CdNO3 for 3h) on whole body uptake and internal distribution of newly accumulated Cd, Ca2+, and Na+ in juvenile rainbow trout (Oncorhynchus mykiss). Fish were fed with three diets 20 (control), 30 and 60mg Ca 2+/g food: for 7 days before fluxes were measured with radiotracers over a 3h period. The two elevated Ca2+ diets reduced the whole body uptake of both Ca2+ and Cd by >50% and similarly reduced the internalization of both newly accumulated metals in most tissues, effects which reflect the shared branchial uptake route for Ca2+ and Cd. As the Ca2+ concentrations of the fluid phases of the stomach and intestinal contents were greatly elevated by the experimental diets, increased gastrointestinal Ca2+ uptake likely caused the down-regulation of the branchial Ca2+ (and Cd) uptake pathway. Waterborne Na + uptake and internal distribution were not affected. While plasma Ca2+ surged after the first two feedings of the 60mg Ca 2+/g diet, internal homeostasis was quickly restored. Total Ca 2+, Na+, and Cl- levels in tissues were not affected by diets. While dietary Ca2+ protected against waterborne Cd uptake, it did not protect against the relative inhibition of waterborne Ca2+ uptake caused by waterborne Cd. Acute exposure to 50μg/l Cd reduced the uptake and internalization of newly accumulated Ca2+ (but not Na+) by 70% or more, regardless of diet. Since elevated dietary Ca2+ reduces waterborne Cd uptake, fish eating a Ca 2+-rich invertebrate diet may be more protected against waterborne Cd toxicity in a field situation. © 2004 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Artigos|
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