Plasma dopamine beta-hydroxylase: a possible aid in the study and evaluation of hypertension.

The activity of dopamine beta-hydroxylase (DBH) in plasma ranged from 2 to 100 units per liter of plasma in 82 apparently healthy subjects (ages 22 to 35 years). A nonnormal pattern of distribution was evident: 62 subjects had values below 35 units (18 +/- 1), while 13 of the remaining 20 subjects had values above 60 units (80 +/- 5). Those with low DBH activity had lower values for urinary catecholamine excretion (31 +/- 3 micrograms), with normal and stable blood pressure; those with high DBH activity had higher values for urinary catecholamine excretion (72 +/- 6 micrograms), with greater lability of arterial blood pressure. The DBH activity was significantly elevated in patients with labile (74 +/- 2 mm-Hg) or fixed (57 +/- 2 mm-Hg) essential hypertension. The results indicate that plasma DBH activity is low and that it falls within a narrow range in young adults with normal and stable blood pressure.