76 

 The interaction effects shown in bone following 

 supplementation indicate increased bone Zn deposition by the 

 ZnLys and CuLys treatments except when combined, in which case 

 bone Zn concentrations drop. This observation might support 

 the theory that when complexed, the mineral is "smuggled" 

 across the membrane by the other molecule's (in this case 

 lysine) transport mechanism (Ashmead and Jeppsen, 1993) . This 

 also seemed to be the case when the sulfate forms were 

 administered together. Copper has been suggested to have a 

 role in the mineralization of growing bone, either in a 

 cuproenzyme with ascorbate oxidase activity, or in its soluble 

 ionic form (Allen and Solomons, 1984) . It was interesting 

 that this situation was not noted with other tissues but this 

 is perhaps due to the fact that regular mineral transport 

 mechanisms may not have been saturated. Following depletion, 

 there was also an interaction effect, this time in kidney Zn 

 concentrations. When ZnLys was the Zn source, CuO treated 

 rats had the highest kidney Zn concentrations and CuS0 4 the 

 lowest, which is puzzling. 



Mean MT concentrations were not affected by Zn source 

 suggesting equal biological values. They were, however, 

 influenced by Cu source as CuO supplemented rats had lower MT 

 concentrations. The levels shown in this study following 

 supplementation were higher and following depletion were 

 similar to those reported for kidney MT (42 ± 3 fig MT/g) by 

 Blalock et al . (1988) following a 14 d supplementation period 



