Renin

Renin: The function of these systems depends on the degree of expression of the renin gene and the conversion of prorenin by proteolytic removal of 43 amino acid prosegments into active renin. Renin is stored in secretory granules of the kidney's juxtaglomerular cells and released in response to various physiological stimuli, such as low blockage of Ang II production or decreases in blood pressure. Sodium intake is the main determinant of renin secretion; low intake or fluid loss reduces the extracellular volume and induces renin secretions. There are three mechanisms which regulate the release of renin. The first is through afferent arteriolar baroreceptors; increases in the release of renin in response to low arterial perfusion pressure. The second is by sympathetic innervation of the juxtaglomerular cells, stimulation of these neurons leads to release of norepinephrine and subsequent stimulation of beta1-adrenergic receptors stimulating the release of renine.