Serum dopamine-beta-hydroxylase in parkinsonism.

Serum dopamine-beta-hydroxylase activities of a group of 16 parkinsonian patients under L-Dopa plus decarboxylase inhibitor showed a distribution with a drift towards higher activities compared to a group of normals of the same age range. Acute doses of L-Dopa failed to cause any change in the serum enzyme activities as well as in the serum concentration of 3-methoxy-4-hydroxyphenylethylene glycol, in parkinsonian patients and in normals. The data support the idea of a limited influence of L-Dopa on the noradrenaline synthesis and release in parkinsonism.