Histochemical study of the effects of cadmium uptake on oxidative enzymes of intermediary metabolism in kidney of goldfish (Carassius auratus)

Uptake of cadmium and histochemical changes of oxidative enzymes-succinate dehydrogenase (E.C.2.3.99.1), cytochrome oxidase (E.C.1.9.3.1) and glucose-6-phosphate dehydrogenase (E.C.1.1.1.49) -in the kidney of Carassius auratus were examined at different times after 10 ppm Cd2+ exposure in very alkaline tap water (346 mg/L HCO3-), which determines a fast and strong precipitation of cadmium as carbonate. A low accumulation of cadmium after 7 days of treatment followed by a gradual increase until the 40th day was observed. The oxidative enzyme activity that resulted was: very weak after 7 days, higher after 24 days and lower after 40 days of treatment. The variations in the enzyme activity along with the accumulation of the metal are interpreted as an increased energy requirement followed by an impairment of mitochondria.