Blood Pressure Regulation, Angiotensin, and Vascular Health

Blood pressure regulation is central to cardiovascular health. It involves a balance between vasoconstriction and vasodilation, influenced by hormones, nutrients, and endothelial function. Disruptions in this balance can contribute to hypertension and vascular damage.

Angiotensin, Blood Pressure, & Vascular Health

Much of the damage done to the vascular endothelium is due to high blood pressure. Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It also stimulates the release of aldosterone from the adrenal cortex to promote sodium retention by the kidneys.

Nutrients have been studied and found to help reduce blood pressure, some by addressing angiotensin, some through other mechanisms. Vitamin D, for example, is associated with lowering levels of angiotensin [1,2]. Magnesium is necessary for vitamin D to be active [3] and is important for the health of the vascular endothelium [4-9]. Low magnesium is associated with increased angiotensin, arterial calcification, and fibrogenesis [10-14].

Hypertension

Clinical cases of hypertension often present with enhanced sympathetic nerve activation [15], resulting in increased vasoconstriction and reduced vasodilation.

The endothelial cells lining the arteries are the frontline of the battle to prevent vascular disease. Inflammation and excessive blood pressure can damage the endothelial cells. Damage attracts white blood cells, which attach to the arterial wall, attracting cholesterol and other fatty materials, as well as calcium, in an attempt to “heal the injury”. This forms “plaque”; which occupies space and narrows the vessel. The plaque can also invade the smooth muscle wall of the artery, making it less supple.

There are a number of vasoactive molecules that also play a role in the maintenance of a balance between vasoconstriction and vasorelaxation. Nitric oxide (NO) is one of these molecules and is released by endothelial cells to promote vasodilation. Angiotensin II is the primary vasoconstrictive hormone. Drugs, like ACE inhibitors are used to block angiotensin.

The Importance of Nitric Oxide

Nitric oxide helps lower blood pressure and ensure cardiovascular health. The vascular endothelium produces NO, which helps relax the smooth muscle of the arteries.

Studies have shown NO can help reduce vascular tone and even help to lower blood pressure [16,17]. Suppressing NO production can cause an increase in blood pressure [18].

Nitric oxide has other physiologic benefits. It is controversial, but some studies show that nitric oxide production enhances exercise performance [19,20]. One analysis of studies using citrulline to increase NO production and improve sports performance suggested that increasing NO was a subtle benefit to exercise performance and may be useful to elite athletes who rely on small advantages to increase performance [21].

These mechanisms are central to overall cardiovascular health and are discussed further in our overview of cardiovascular function.