The estimation of renin in plasma by an enzyme kinetic technique

Abstract

A method has been developed for the measurement of renin in rabbit plasma; the method is based on the initial velocity of angiotensin formation when renin is incubated with angiotensinase-free substrate prepared from ox serum. A calibration graph is constructed relating the initial velocity of angiotensin formation to renin concentration when a range of dilutions of standard rabbit renin are incubated with a prepared substrate. The initial velocity of angiotensin formation is used to determine the renin concentration of plasma. Renin is extracted from plasma by absorption on diethylaminoethylcellulose, eluted, and acidified to remove traces of angiotensinase. Recoveries, though low (40%), are consistent, and the method can be used to measure renin in the peripheral plasma of normal rabbits.