1 In humans CaNa 2EDTA increases urinary excretion of lead as well as that of essential metals such as zinc, ferrum and manganese but not that of copper.
2 We studied the effect of CaNa2EDTA injection on serum dopamine-β-hydroxylase, a copper-dependent enzyme, in three male lead welders hospitalized for suspected lead poisoning.
3 injection of CaNa 2EDTA (1000 mg i.v.) resulted in rapid reduction of serum dopamine-β-hydroxylase activity which returned to normal level within 24 hours.
4 Copper sulphate (8 μM) but not ethylmaleimide (10 mM) restored in vitro serum dopamine-β-hydroxylase activity to pre-dosing values which indicates that CaNa2EDTA inhibits dopamine-β-hydroxylase by removing copper from the enzyme.
5 An inverse dose effect relationship between injected CaNa2EDTA and residual serum dopamine-β-hydroxylase activity was observed.
6 In spite of the reported lack of changes in copper serum concentration, CaNa2EDTA significantly affects the activity of a copper-dependent enzyme in the serum.
7 As CaNa 2EDTA is currently the drug of choice for the treatment of asymptomatic lead poisoning in children, the effect of CaNa2EDTA on copper-enzymes requires further investigation.
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