Renin

Renin, also known as angiotensinogenase, is a circulating enzyme released mainly by juxtaglomerular cells in the juxtaglomerular apparatus of the kidneys in response to low blood volume or decreased serum NaCl concentration, mediated through the rapid release of prostaglandins. Although it has hormone-like actions, it cleaves a protein precursor in the circulation rather than working on a cellular target. Thus it is not truly a hormone. Sympathetic activation of membrane β1- and α1-adrenergic receptors on JGA cells also cause renin release, probably by altering tubular sodium content or macula densa function. The normal concentration in adult human plasma is 1.98-24.6 ng/L in the upright position. Renin is pronounced "Ree-nin" or "Rē-nin" (IPA: ).