Alteration of the volume-renin component in borderline essential hypertension

Interrelations between blood pressure, circulatory volumes and the renin-angiotensin system were studied in 15 normal subjects and in 25 young patients with borderline hypertension after equilibration on controlled sodium intake. Total blood and plasma volumes were consistently lower and plasma renin activity higher in borderline hypertensive as compared to normotensive controls. The decreased volumes were inversely correlated with blood pressure and plasma renin activity, but no correlation was found between blood pressure and plasma renin activity or the product of circulating renin and volumes. The fact that blood pressure and plasma renin activity were independently correlated to circulating volumes but did not correlate between themselves would suggest a common causal factor for the three observed phenomena: elevated renin, decreased volume and borderline hypertension; these anomalies of the volume-renin axis might be mediated through the well documented hyperresponsiveness of the sympathetic nervous system in these patients.