Angiotensin I is formed by the action of renin on angiotensinogen. Renin is produced in the kidneys in response to renal sympathetic activity, decreased intrarenal blood pressure at the juxtaglomerular cells(2), or decreased delivery of Na+ and Cl- to the macula densa. If less Na+ is sensed by the macula densa, renin release by juxtaglomerular cells is increased. Renin cleaves the peptide bond between the leucine and valine residues on angiotensinogen, creating the ten-amino acid peptide angiotensin I appear to have no biological activity and exists solely as a precursor to angiotensin 2 [2][3][4].