ARBs & ACE Inhibitors...Powerful Blood Pressure Treatments

There are many important factors that together keep the blood pressure at a certain level. A central role in maintaining the blood pressure is played by a chain of key hormonal reactions. The first step in the chain is the production of renin in the kidneys when the kidneys detect lower blood pressure. The renin stimulates the formation of a protein called angiotensin I, which is then converted to angiotensin II by the angiotensin- converting enzyme in the lungs. Angiotensin II is the most powerful constrictor of blood vessels known. This effect of constricting blood vessels tends to elevate the blood pressure. Angiotensin II also causes the secretion of an additional blood pressure elevating hormone in the adrenal glands, called aldosterone.

This chain of blood pressure regulating hormones is referred to as the renin-angiotensin-aldosterone (RAA) hormonal system.

The RAA system has long been known to be important in regulating the blood pressure in the body. Many factors affect the functioning of this system including genetics (i.e., heredity, including race), diet, weight, activity, and certain medications.

Several classes of blood pressure lowering (anti-hypertensive) medications may have some effects on this hormonal system. However, two classes of drugs have the most substantial effects on the RAA system. These two classes are the angiotensin receptor blockers (ARB drugs) and the angiotensin converting enzyme inhibitors (ACE inhibitors). Both of these classes of drugs lower blood pressure by blocking certain specific steps in the RAA chain.