renin re·nin (rē'nĭn, rěn'ĭn)
A protein-digesting enzyme that is released by the kidneys and that catalyzes the hydrolysis of angiotensinogen to angiotensin I. Also called angiotensinogenase.
A proteinase enzyme of high specificity that is released by the kidney and acts to raise blood pressure by activating angiotensin. See also angiotensin.