Product Information: Renin Activity Fluorometric Assay Kit: simple, rapid & convenient method to detect renin activity as low as 0.75 U/ml. 100 assays. Background: 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