Renin-angiotensin system
The renin-angiotensin system is a "blood pressure regulating system of interacting components that include renin; angiotensinogen; angiotensin converting enzyme; angiotensin I; angiotensin II; and angiotensinase."[1]
Physiology
"Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming angiotensin I. angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to angiotensin II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal vascular smooth muscle, leading to retention of salt and water in the kidney and increased arterial blood pressure. In addition, angiotensin II stimulates the release of aldosterone from the adrenal cortex, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down bradykinin, a powerful vasodilator and component of the kallikrein-kinin system."[1]
Clinical significance
Several classes of medications affect the renin-angiotensin system. Randomized controlled trials have investigated the use of the latter two classes together for a synergistic effect, but have found increased adverse effects with no added benefit from their combination.[2]
Direct renin inhibitors
Aliskiren is an oral direct renin inhibitor that according to a randomized controlled trial may have "renoprotective effects that are independent of its blood-pressure-lowering effect in patients with hypertension, type 2 diabetes, and nephropathy."[3]
Angiotensin-converting enzyme inhibitors
Angiotensin-converting enzyme inhibitors are medications used for the treatment of hypertension and heart failure.
Angiotensin II receptor antagonists
Angiotensin II receptor antagonists are medications that antagonize the angiotensin II type 1 receptor and are used for the treatment of hypertension.
References
- ↑ 1.0 1.1 Anonymous (2024), Renin-angiotensin system (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ McMurray JJ (April 2008). "ACE inhibitors in cardiovascular disease--unbeatable?". N. Engl. J. Med. 358 (15): 1615–6. DOI:10.1056/NEJMe0801925. PMID 18378521. Research Blogging.
- ↑ Parving HH, Persson F, Lewis JB, Lewis EJ, Hollenberg NK (June 2008). "Aliskiren combined with losartan in type 2 diabetes and nephropathy". N. Engl. J. Med. 358 (23): 2433–46. DOI:10.1056/NEJMoa0708379. PMID 18525041. Research Blogging.