The effect of dietary zinc status on biliary metal excretion of rats.
The effect of dietary zinc status on biliary excretion of zinc, cadmium and mercury administered as a bolus of metal chloride (1 mg metal/kg body weight i.v.) was studied. Female rats were fed a purified diet containing either 9 micrograms/g (low), 45 micrograms/g (adequate) or 1150 micrograms/g (high) zinc for 8 d. Hepatic metallothionein (MT) was similar in low- and adequate-zinc groups, but was 18-fold higher in the high-zinc group than in the other two groups. Liver zinc content varied in relation to dietary zinc level. Biliary excretion of all metals studied was significantly lower in the high-zinc group than in the low-zinc group. The cumulative excretion of zinc, cadmium and mercury over 2.5 h in rats fed these two diets was 6.2 +/- 1.4 vs. 33.5 +/- 7.7, 0.006 +/- 0.02 vs. 22.8 +/- 8.4 and 1.6 +/- 0.6 vs. 14.9 +/- 5.3 micrograms/kg body weight, respectively. A relationship was found between the disposition of metal in liver and the extent of biliary metal excretion. Biliary metal excretion was highly correlated with liver cytosolic non-MT-bound metal; r = 0.999, 0.998 and 0.993 for endogenous + exogenous zinc, cadmium and mercury, respectively.
Jaw
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Division of Nutritional Sciences, University of Illinois, Urbana-Champaign 61801.
Jeffery
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EH
D000818:Animals; D001646:Bile / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism*; D019256:Cadmium Chloride; D002712:Chlorides / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D003600:Cytosol / Q000378:metabolism; D004032:Diet; D005260:Female; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008627:Mercuric Chloride / Q000378:metabolism*; D008668:Metallothionein / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013054:Spectrophotometry, Atomic; D015032:Zinc / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D017967:Zinc Compounds
D002712:Chlorides; D017967:Zinc Compounds; D002104:Cadmium; D008627:Mercuric Chloride; C016837:zinc chloride; D008668:Metallothionein; D015032:Zinc; D019256:Cadmium Chloride