Catecholamines in Plasma and Urine in Patients with Essential Hypertension Determined by Double‐Isotope Derivative Techniques

Employing double-isotope derivative techniques, noradrenaline and adrenaline have been determined in plasma and in urine and dopamine in urine in 21 patients with essential hypertension as well as in 32 controls. Plasma noradrenaline rose with age in both groups of subjects. No differences were observed in plasma noradrenaline and plasma adrenaline in the resting supine position and in urinary excretion of noradrenaline and dopamine in hypertensive patients as compared to control subjects. Urinary excretion of adrenaline was somewhat lower in the hypertensives than in the controls. Treatment with alprenolol, a beta-adrenergic blocking agent, did not influence noradrenaline and adrenaline in plasma in the basal state or the urinary excretion of the three catecholamines. The combined treatment with alprenolol and hydralazine was followed by a significant rise in plasma noradrenaline. It is concluded that the adrenergic activity evaluated by circulating catecholamines is normal in most patients with essential hypertension.