Dopamine-beta-hydroxylase after treatment with beta-blockers in hypertension

Dopamine-beta-hydroxylase (DBH) the enzyme responsible for the biosynthesis of noradrenaline from dopamine, was assayed in the blood plasma of 19 cases with hypertension before and during beta-receptor blockade. Propranolol was given to 15 patients and I.C.I. 66,082 (a new cardioselective beta-adrenergic blocker without intrinsic sympathomimetic properties) to 4 patients. - There was no effect by the drugs on the level of plasma DBH activity in spite of a good reduction of the blood pressure.