
Angiotensin II is the primary regulator of renal aldosterone secretion and a potent vasoconstrictor. It is generated through the renin angiotensin system (RAS): circulating angiotensinogen is cleaved by renin to form angiotensin I, which is then converted to angiotensin II via angiotensin converting enzyme (ACE). The rate-limiting step in the RAS is renin secretion by the renal juxtaglomerular cells, modulated by renal blood flow. Low renal blood flow and low perfusion pressure increases renin secretion, stimulating angiotensin II and aldosterone production with a resulting increase in blood pressure and renal sodium retention. These changes then produce inhibition of renin secretion and complete the feedback control loop.