Studies on the uptake and subsequent tissue distribution of [35S]trithiomolybdate in rats: effects on metallothionein copper in liver, kidney, and intestine.

[35S]trithiomolybdate (20 micrograms Mo) was readily absorbed from intestinal sacs in anesthetized rats, and radioactivity was subsequently detectable in all the subcellular fractions examined in the organs sampled. The compound was bound reversibly to proteins in patterns similar to those observed in liver in cattle and sheep. Absorption was depressed by the presence of copper in the sacs. At higher levels of trithiomolybdate (1 mg Mo per rat), the characteristic copper peak of metallothionein disappeared from the liver, kidney, and intestine cytosol fractions in most animals, while the concentration of copper in plasma increased by about 50%. It is suggested that the changes in copper distribution are relevant to the clinical syndromes produced by increased dietary Mo in ruminants.