Section 7
Chapter 6,810

Tissue accumulation and enzymatic effects of hexavalent chromium in rainbow trout salmo gairdneri

Buhler, D.R.; Stokes, R.M.; Caldwell, R.S.

Journal of the Fisheries Research Board of Canada 34(1): 9-18


DOI: 10.1139/f77-002
Accession: 006809387

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Two year old rainbow trout (S. gairdneri), reared for 2 yr in water containing about 0.00025 mg/l hexavalent Cr+6 (Naches trout) or between 0.002-0.010 mg/l Cr+6 (Hanford trout) accumulated appreciable Cr, yielding whole body residues of about 0.029 and 0.18 .mu.g/g wet tissue, respectively. Highest concentrations were in the opercular bone, spleen, kidney, gastrointestinal tract and gall bladder. Short-term exposure of Hanford trout to 2.5 mg/l Cr+6 caused a rapid additional increase of tissue Cr, but at 22 days whole body levels were only 0.87 .mu.g/g. On return of exposed fish to water containing 0.002-0.010 mg/l Cr, the metal was rapidly depleted from most tissues except kidney, liver, gill, gall bladder and bile. Cr accumulated in tissues of trout exposed to 2.5 mg/l Cr+6 was not distributed proportionally among the various subcellular fractions, but concentrated in the cell cytosol, especially in the liver and gill. Mitochondrial cytochrome oxidase, NADH-cytochrome c reductase and succinate cytochrome c reductase activities in liver, kidney, gill and brain tissues of Naches trout, Hanford trout and Hanford trout exposed to 2.5 mg/l Cr+6 were not significantly different except for kidney NADH-cytochrome c reductase, which was lower in Hanford and Cr treated fish. Microsomal nitroreductase, O-demethylase and NADPH-cytochrome c reductase and the soluble glucose-6-phosphate dehydrogenase activities in liver and kidney from Hanford trout were significantly lower than those of Naches trout. Exposure of Hanford trout to 2.5 mg/l Cr+6 did not reduce the activities of these enzymes below control levels. In vitro studies showed that trout enzymes were fairly insensitive to Cr+6 inhibition. Observed differences in enzyme activity between Naches and Hanford trout may be caused by factors other than Cr content of the water.

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