Biochemical changes in the tissues of animals injected with iron: acid phosphatase and other enzymes

Abstract

1. Very high doses of iron, as iron-dextran or saccharated iron oxide, injected into mice, bring about stunting of growth and hyperplastic enlargement of the liver. There is a disproportionately large, and apparently permanent, increase in the acid-phosphatase activity of liver. Enhanced activity is seen in the liver of the rat and the hamster, but not of the guinea pig. 2. Injection of iron in doses which were less massive, yet well above the clinical level, or the administration of sodium chloride solution or dextran, had no such result. 3. In the mouse and rat the injection sites in muscle and in subcutaneous tissue have a raised acid-phosphatase activity after the administration of heavy doses of iron-dextran. The spleen and kidney of the mouse also show a higher level of acid phosphatase. 4. Of various other enzyme activities measured in the siderotic liver, the following were significantly raised: cathepsin, B-glucuronidase, alkaline phosphatase, arylsulphatase, acid ribonuclease, acid deoxyribonuclease and adenosine triphos-phatase. 5. The significance of these observations is considered in the light of the possible relationships between intracellular iron and acid phosphatase on the one hand, and cytoplasmic particles or structures on the other. It is suggested that the observed changes may be partly lysosomal in origin but that the activity of macrophages and related cells is likely to be a contributory factor.