Serum Dopamine β-Hydroxylase Activity in Essential Hypertension

1. Serum dopamine β-hydroxylase activity was determined in normotensive control subjects and patients with labile or established essential hypertension. The enzyme activity was 25·9 ± 1·9 (sem), 29·6±2·5 and 25·1 ± 1·9 μmol min —1 1 —1 , for control, labile and established hypertensive subjects respectively. 2. Neither blood pressure nor serum dopamine β-hydroxylase activity was changed in normotensive control subjects by administration of phentolamine; however, in patients with essential hypertension blood pressure was significantly decreased ( P 3. Our results suggest that there is no correlation between serum dopamine β-hydroxylase activity and blood pressure.