Sympathetic reactivity to upright posture in borderline and established hypertension.

Plasma and urinary catecholamines and their metabolites were estimated in 18 patients with borderline hypertension (BH), 27 patients with established hypertension (EH) and 15 healthy subjects in basal conditions and after 20-min standing. Patients with EH differed from the remaining groups, showing decreased urinary excretion of noradrenaline (NA). In patients with BH, in comparison with controls, an augmented plasma NA in basal conditions as well as a more pronounced increment of plasma NA in response to upright posture was observed. Moreover, in BH increased urinary excretion of dopamine, homovanillic acid and 3-methoxy-4-hydroxyphenylglycol has been found. In patients with BH the increase of diastolic blood pressure in response to upright posture was associated with an exaggerated increase of plasma NA and adrenaline. The results of the study show that patients with BH are characterized by sympathetic overactivity and suggest that in this type of hypertension this factor may play a role in response of blood pressure to physiological stimuli.