[Plasma dopamine beta-hydroxylase activity in clinically healthy children]

Dopamine-beta-Hydroxylase is the enzyme that catalyzes the conversion of dopamine to norepinephrine. Plasma D beta H activity was measured with spectrophotometric method in 60 healthy children of various age groups. Plasma D beta H activity is influenced by age: the means reveal a progressive rise in activity with each successive age group. Also, a great individual variation was found. Therefore, measurement of D beta H activity is not a good indication of the activity of the simpathetic nervous system, except in special pathological conditions. Moreover, the wide range of activities among normal human subjects might indicate important factors in determining the plasma D beta H level. The possibility of a genetic control must be considered.