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.
Original language | English (US) |
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Pages (from-to) | 57-73 |
Number of pages | 17 |
Journal | Aquatic Toxicology |
Volume | 67 |
Issue number | 1 |
DOIs | |
State | Published - Mar 30 2004 |
Keywords
- Cadmium uptake
- Calcium uptake
- Dietary calcium
- Fish
- Sodium uptake
ASJC Scopus subject areas
- Aquatic Science