Renin activity determination using human plasma as a substrate.

A method for human renin activity determination using human plasma as the substrate is described. Angiotensin I is generated by incubating renin with human plasma, which is available along with the commercial radioimmunoassay kit for angiotensin I. The method obviates the need to isolate and purify the substrate, human angiotensinogen, from human plasma. In addition, the assay is highly renin specific, sensitive, and convenient to use for the routine determination of active human renin during its isolation and purification from tissue extracts or from genetically engineered bacterial and nonbacterial expression systems.