[Effect of cadmium on calcium absorption of the rat duodenum].
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Biomedical subjects
Publications and source records attributed to C Sugawara.
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Fischer rats were a fed diet supplied with copper chloride (150-600 ppm) for 60 d from weaning. Serum (glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) activities were increased with the increase of Cu concentration in the diet. Biliary excretion of Cu was related to the dietary Cu level. Depositions of hepatic and renal Cu were also related to the dietary Cu level in a dose-dependent manner. In particular, hepatic (155.2 +/- 13.3 micrograms/g) and renal (44.9 +/- 4.4 micrograms/g) Cu concentrations increased abruptly in the Cu-600 ppm group. In the liver, about 60% of Cu was distributed in the soluble fraction (100,000 g supernatant). In the Cu-600 ppm group, 25% of cystosolic Cu was bound to metallothionein (MT). Our results suggest that chronic exposure to Cu appears to have a deleterious effect on the hepatic function, and further, that even in rats with normal biliary Cu excretion, clearance of Cu from the liver may be marginal when dietary Cu is near the 600-ppm level. Although Cu is an essential nutrient, an overload of Cu should be avoided.
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.