Renin (EC 3.4.23.15), also known as an angiotensinogenase, is an enzyme that participates in the renin-angiotensin system (RAS) which mediates extracellular volume (i.e. blood plasma, lymph and interstitial fluid), and arterial vasoconstriction. An over-active renin-angiotensin system leads to vasoconstriction and retention of sodium and water, causing hypertension. Renin inhibitors are widely used for the treatment of hypertension. In BioVision’s Renin Activity Assay Kit, Renin and other proteases hydrolyze the FRET substrate resulting in a product that is detected fluorometrically at Ex/Em = 328/552 nm to give total protease activity. In the presence of a Renin-Specific Inhibitor, hydrolysis of the substrate is only due to the non-specific protease activity. The difference between the total activity and the activity in the presence of Renin Specific Inhibitor, gives the Renin Activity in the sample. This rapid, simple & sensitive kit can detect renin activity as low as 0.75 U/ml.