Renin , a polypeptidic enzyme (MW~ 40000) also known as angiotensinogenase, is a circulating protease secreted by juxtaglomerular cells in the juxtaglomerular apparatus of the kidneys in response to low blood volume or low body NaCL content. Renin activates the renin-angiotensin system by cleaving angiotensinogen produced in the liver into angiotensin I (inactive) which is further converted into angiotensin II (active) in the vascular epithelium of the lung. Angiotensin II can cause vasoconstriction by stimulating the central nervous system , in addition it stimulates ADH (antidiuretic hormone) secretion and aldosterone secretion from the adrenal gland.Regulation of blood pressure and renal glomerular filtration control are the most important functions of renin -angiotensin system . Plasmatic concentration of renin is influenced by concentration of circulating angiotensinogen and subsequently the concentration of angiotensin II. High plasmatic levels of angiotensin II reduce renin secretion.(negative feed back) Determination of renin plasma levels is useful in the diagnosis of hypertension and in the therapeutic follow up of hypertensive patients. Plasmatic concentration of renin decreases in patients with hypertension due to a primary hyperaldosteronism , contrary to renovascular hypertension where concentrations of renin and aldosterone are both elevated.
- References to Renin (Angiotensinogenase, REN)