Biliary excretion of copper in Fischer rats treated with copper salt and in Long-Evans cinnamon (LEC) rats with an inherently abnormal copper metabolism

Abstract

Increased biliary Cu excretion was found in Fischer rats injected with Cu. The biliary Cu was located at the void (large-molecule region) and total (small-molecule region) volume of a Sephadex G-75 column. The most Cu was found in the total volume. The two Cu peaks comigrated with absorbance at 280 nm. Although the bile from Cu-untreated Fischer rats did not show Cu absorbance in the total volume, absorbance at 280 nm was also found in this region. Even though Long-Evans Cinnamon (LEC) rats deposited a gross amount of Cu (194.0 +/- 27.8 micrograms/g liver) in the liver, they conversely showed reduced Cu excretion into the bile. LEC bile did not show Cu absorbance but rather absorbance at 280 nm in the total volume. Therefore, it seems unlikely that the small molecules found in the Sephadex G-75 regulate biliary Cu excretion in Cu-loaded rats, although the molecules bind to Cu. When the bile from Cu-untreated Fischer and LEC rats was incubated with CuCl2 solution, the most Cu was recovered in the total volume of this column. Our results suggest that reduced biliary Cu excretion in LEC rats is not related to the small molecules, and that Cu cannot be excreted in the form of macromolecules in rats to decrease Cu from the Cu-loaded liver.