Relationship Between Plasma Catecholamines and the Renin-Aldosterone System During Exercise in Normal and Essential Hypertensive Subjects

Abstract

Interrelations were investigated between blood pressure, plasma epinephrine (E), norepinephrine (NE), dopamine (D), aldosterone, cortisol concentrations, active and inactive plasma renin activity (PRA), and age in 21 normotensive subjects (aged 20-60 years) and in 25 patients (aged 20-63 years) with essential hypertension (EH). These parameters were measured at rest and during exercise on a bicycle ergometer. In normotensive subjects basal and exercise-stimulated levels of plasma NE increased with age which was not observed in EH. In hypertensive patients there was a higher plasma D concentration under the exercise as compared with normotensive controls. In the normotensives, basal active PRA was inversely related to age (p less than 0.05), and during initial 8 min of exercise active PRA significantly correlated with plasma E and plasma NE. Moreover, absolute changes from basal to acutely stimulated values of active PRA were directly related to the changes of plasma E and NE (p less than 0.001). In hypertensive patients these relationships were not found. However, in the hypertensives there were significant positive correlations between the increases of active PRA, plasma E, plasma NE on the one hand and their respective basal values on the other hand. The results indicate very strong functional relationship between the sympathetic-adrenomedullary and renin-angiotensin systems during initial interval of acute stimulation in normotensive subjects. Essential hypertension is not a pathophysiologically homogenous disease with respect to reactivity and interaction of plasma catecholamines and PRA. Separate regulatory pathways exist for plasma active and inactive renin. During short-time exercise aldosterone secretion is related rather to the renin-angiotensin system than to the hypothalamic-pituitary axis.