[Significance of noradrenaline in the pathogenesis of essential hypertension. Preliminary report].

The pathogenic role of the sympathetic system in essential hypertension was evaluated by combined analysis of urinary and plasma catecholamine levels and pressor sensitivity to endogenous noradrenaline. The latter was estimated indirectly by the ratio between percentile changes in blood pressure and plasma noradrenaline following adrenergic neuronal blockade with the agent debrisoquine. In normal and mildly hypertensive (141/91 to 160/105 mm Hg) subjects, supine or upright plasma levels and excretion rates of noradrenaline correlated (p less than 0.01) with age and were comparable; no correlation was present in patients with moderate to severe hypertension (greater than 160/105 mm Hg) who tended to have supernormal noradrenaline levels under the age of 40 years. Adrenaline values were normal in essential hypertension. Pressor sensitivity to noradrenaline was comparable in normal and mildly hypertensive subjects (0.03 +/- 0.08 [SE] and 0.17 +/- 0.04, respectively) but increased (p less than 0.001) in moderate to severe hypertension (0.62 +/- 0.11). These findings suggest that moderate to severe essential hypertension may be maintained, at least partly, by the inappropriate association of normal plasma noradrenaline levels with increased noradrenaline pressor sensitivity. This may also provide a rational basis for the use of pharmacologic adrenergic inhibition in the treatment of moderate to severe essential hypertension.