PARENT SESSION
TP8 - Fate & Effects of Metals: Aquatic Biology
Chair: Playle, Rick¹, ¹ Wilfrid Laurier University, Waterloo, ON
Co-chair: Green, Andrew², Lee, Chris³, ² International Lead Zinc Research Organization, Inc, Research Triangle Park, NC³ International Copper Association, Ltd., New York, NY
2:10 PM to 5:30 PM - Tuesday, 19 November 2002
Room Ballroom C

(475) Plasma clearance of cadmium and zinc in rainbow trout: implications for metal homeostasis.Plasma clearance of cadmium and zinc in rainbow trout: implications for metal homeostasis.

Chowdhury, M^*,1, Kamunde, C¹, Grosell, M¹, McDonald, D¹, Wood, C¹, ¹ McMaster University, Hamilton, ON, Canada

ABSTRACT- Chronic effects of metals in fish are not yet well defined. We characterized the plasma clearance of cadmium (Cd) and zinc (Zn) in rainbow trout (Oncorhynchus mykiss) by exposing the fish (~0.3 kg) to waterborne Cd (3 g/L) or Zn (150 g/L) for 30 days, followed by a single bolus of ¹⁰⁹Cd (7g/kg) or ⁶⁵Zn (12 g/kg) injected into the vascular system through indwelling arterial catheters in order to reveal the effect of metal acclimation on clearance kinetics. Plasma clearance of Cd in Cd-acclimated fish was faster than that in non-acclimated trout, while the levels of Cd in red blood cells were 1.2 - 2.2 times higher in Cd-acclimated fish than in non-acclimated fish. Plasma clearance of Zn was substantially lower than Cd clearance. Acclimation to waterborne Zn reduced the new Zn levels in red blood cells, but did not affect the clearance of Zn from blood plasma. Rainbow trout were also acclimated to dietary Cd (500 mg/kg diet) for 30 days and subsequently gastrointestinal ultrastructure and uptake and plasma clearance of radiolabelled Cd (290 g/kg) infused into the gut via stomach catheters were examined. Acclimation to dietary Cd increased the uptake rate of Cd into the blood plasma but did not affect the clearance kinetics of Cd from the plasma. Morphological changes observed in the gut of the dietary Cd-exposed fish included mucus cell and eosonophilic granule cell proliferation, increased number of lysosomes, and increased apoptosis. We conclude that metal-acclimation plays an important role in the internal metal handling by trout for the non-essential metal, cadmium and the essential metal, zinc. (Supported by NSERC Strategic, ILZRO, NiPERA, ICA, Falconbridge, Cominco, and Noranda).

Key words: cadmium, zinc, homeostasis, trout