Effect of Zinc on Cytochrome Oxidase Activity

Abstract

Zn, fed at relatively high levels, resulted in lowered growth, hemoglobin concn., and cytochrome oxidase activity in the rat. Addition of Cu to the Zn diet improved the growth and hemoglobin concn. of the animals on this diet, but to subopt. levels, while the cytochrome oxidase of the heart tissue was increased to a greater-than-normal level. It appears that the synthesis of cytochrome oxidase takes precedence over that of hemoglobin. A highly significant correlation was found between hemoglobin level and cytochrome oxidase activity. The inhibitory effect of Zn was apparently not due to the presence of free Zn ions in the heart homogenate, since in vitro addition of inorganic Zn to homogenates of normal rat hearts, in amts. equivalent to that found in the hearts of Zn-toxic animals, did not result in a lowering of cytochrome oxidase activity.