[Plasma concentration of noradrenaline in essential arterial hypertension].

Plasma norepinephrine concentrations after supine rest and after standing were measured by high-pressure liquid chromatography with electrochemical detection in 49 normotensive controls and in 79 patients with essential hypertension. Twenty-nine hypertensive patients were not treated for hypertension. In normotensive subjects--but not in hypertensive patients--supine plasma norepinephrine levels increased significantly with age. No significant difference in supine plasma norepinephrine levels was found between hypertensive patients (NE = 0.28 +/- 0.16 microgram/l, n = 79 and NE = 0.28 +/- 0.14 microgram/l, n = 29) and normotensive subjects (NE = 0.30 +/- 0.13 microgram/l). When expressed as percentage, the rise in norepinephrine levels when standing was greater in hypertensive patients (127.4 +/- 77.4%, n = 79 and 122.6 +/- 65.6%, n = 29) than in normotensive subjects (93.2 +/- 60.3%). When patients and controls aged less than 40 years were compared, similar results were obtained. Supine plasma norepinephrine levels do not support the theory that sympathetic system activity is enhanced in essential hypertension.