Plasma catecholamines in primary hypertension

Abstract

In 60 patients with primary hypertension and 23 normotensive healthy subjects of comparable age, blood pressure, heart rate, and plasma catecholamine concentration were measured in the recumbent and upright positions and in some during isometric handgrip exercise. Plasma catecholamines were measured by a sensitive radioenzymatic assay. Plasma norepinephrine was significantly higher in the recumbent and upright position and increased significantly more during exercise in the hypertensive than in the normotensive group. Twenty-five percent of the hypertensive patients had plasma norepinephrine levels greater than 2 standard deviations above the mean of the normotensive group. Plasma norepinephrine was significantly correlated with age in both groups of subjects and with blood pressure in the hypertensive group only. However, age was significantly correlated with blood pressure in both groups. During exercise, blood pressure increased slightly less in the hypertensive than in the normotensive group, despite the significantly greater rise in the catecholamines in the hypertensive than in the normotensive group. It is concluded that the elevated plasma NE may reflect increased sympathetic activity, which could account for elevation of blood pressure in primary hypertension.