AGE-RELATED-CHANGES IN THE BINDING AND UPTAKE OF CU, ZN SUPEROXIDE-DISMUTASE IN RAT-LIVER CELLS

The present paper reports the effect of aging on receptor mediated end ocytosis of Cu, Zn superoxide dismutase in rat liver cells. The fate o f bovine Cu, Zn superoxide dismutase conjugated to colloidal gold was followed by electron microscopy in young (2 months) and old (24 months ) rats in situ, in vivo and in vitro experiments. The use of different models for the study of the binding and internalization of the enzyme allowed to discriminate the contribution of each different liver cell type, The data obtained demonstrate that aging of the liver affects b inding and uptake of this enzyme. In particular both the number of bin ding sites and the rate of internalization were depressed in old rats. Therefore, the hypothesis of therapeutic application of superoxide di smutase for age-related diseases needs to be revalued in view of the f act that receptor-mediated endocytosis of this protein is a mechanism affected by senescence.