INCREASED PLASMA R E N l N SUBSTRATE CONCENTRATIONS IN H U M A N MALIGNANT HYPERTENSION

In normal man, an inverse relationship between plasma renin activity (PRA) and renin substrate (RS) levels is observed (Rosset & Veyrat, 1971). In situations entailing an inhibition of the renin-angiotensin system (RAS), achieved by deoxycorticosterone (DOC) plus salt diet, PRA level is decreased, as RS level is increased; when the RAS is activated, by salt depletion, PRA level is increased and RS level is decreased. Is this inverse relation also present in human pathological conditions characterized by an inhibition or an activation of the RAS? Primary aldosteronism and bilateral nephrectomy were the two conditions chosen for studying a chronic inhibition of the RAS. On the other hand, malignant hypertension (MH) is the chronic condition of extreme elevation of the RAS elicited, because MH is commonly accompanied by a potent activation of the RAS, by the spasm of the small arteries, especially of the kidneys. This activation is responsible for the secondary hyperaldosteronism.