URINARY PROTEIN EXCRETION OF SEMIDOMESTICATED MINK IN A CHRONIC METHYLMERCURY STUDY

A model using semidomesticated mink was set up to study the effects of chronic oral methylmercury exposure in piscivorous mammals. Three gro ups of mink were fed daily with diets containing approximately 0.1, 0. 5, and 0.9 mu g/g of total mercury. Piscivorous and non-piscivorous fi sh, naturally contaminated with methylmercury, were used to prepare di ets. Renal injury was evaluated using total urine protein/creatinine r atio and differentiation of urinary low-molecular-weight and high-mole cular-weight proteins on sodium dodecyl sulfate polyacrylamide gel ele ctrophoresis (SDS-PACE). The significance of the total urine protein/c reatinine ratio data was assessed by comparing the results to a 95% gr oup-based reference interval. The values for total urine protein/creat inine ratio did not reveal any significant increased excretion, and no dose-related trends were observed within the reference interval. Over all the total urine protein data did not suggest renal damage. Analysi s of the SDS-PACE electrophoretograms did nor suggest the presence of any persistent glomerular damage in any group. High-molecular-weight p roteins were not detected more frequently for any of the dose groups. During the adaptation phase, the B2M-like protein band was not remarke d during the visual analysis of the gels. The B2M-like protein band wa s remarked during the gel analysis only several weeks into the exposur e phase. This B2M-like protein band wits more prevalent in urine sampl es taken from minks in the 0.5 and 0.9 mu g/g groups than in the 0.1 m u g/g group. These latter data, however, did not allow an evaluation o f a quantitative dose-response excretion with time. The B2M-like data are suggestive of very minor renal injury.