Influence of dietary molybdenum on the metabolism of intravenously injected radioactive copper in the rat.

Control and molybdenum-supplemented rats (Mo rats) were injected i.v. with 64Cu or 67Cu. The distribution of radioactivity over plasma, liver, and kidney, as well as the intracellular distribution in these organs, was studied as a function of time. Compared with control rats, the level of radioactive Cu in the plasma of Mo rats was increased. The results for liver and kidney of Mo rats had to be corrected for a decrease in specific activity of 64Cu; they suggested that the 64Cu release from the liver and the 64Cu uptake in the kidney of Mo rats ran parallel to that in control rats for up to 8 hr; after which, an increase in both organs of the Mo-rats followed. 64Cu in the subcellular particles and in a high molecular weight (MW) protein of the cytoplasma of the organs of Mo rats was increased compared with control rats. In control rats the transport of 64Cu from a 10,000 MW protein to a 30,000 MW protein of the cytoplasma of the kidney seemed to be much slower compared with that of the liver, but Mo had no influence on this process in either liver or kidney.