An inactive higher-molecular-weight renin in normal subjects and hypertensive patients.

Inactive renin which can be converted to an enzymologically active form by acidification to pH 3-3 by dialysis was found in normal subjects and in patients with untreated essential hypertension. The molecular weight of this inactive renin (43 000) is 2000 +/- 900 (S.E.M.) daltons higher (p less than 0.05) than that of naturally occurring active renin and the two forms of renin could be clearly separated by ion-exchange chromatography with diethylaminoethyl-"Sepharose'. Patients with low-renin essential hypertension had proportionately larger amounts of inactive renin than usual, so that the total renin in these patients approached the normal range. Inactive renin seems likely to be a form in which the enzyme is secreted since in a patient with renal-artery stenosis its concentration was greater in the renal-vein blood coming from the affected kidney.