What is Cerebrovascular Disease (CVD)?
So, what is this cerebrovascular disease that is killing millions worldwide?
Cerebrovascular refers to the blood vessels (arteries) that supply blood to the brain, and cerebrovascular disease, in simple terms, refers to an abnormality of the brain due to a disruption in this blood supply in some way. This causes the brain cells to be deprived of oxygen as the blood is responsible for carrying oxygen to all of our body cells. The brain cells will then die or be damaged under this condition.
The most common type of cerebrovascular disease is stroke, also known as cerebrovascular accident. Stroke is caused by either a clogged blood vessel in the brain, or when the blood vessel in the brain bursts or leaks. Other CVD include: transient ischemic attack (TIA), multi-infarct (arteriosclerotic) dementia and reversible ischemic neurologic deficit (RIND).
Roles of Nitric Oxide (NO)
Nitroglycerin and related vasodilating compounds increase the diameter of a blood vessel, and were found to act to release nitric oxide, an endothelium-derived relaxing factor (EDRF). Endothelium cells are cells that line the blood vessels and prevents the interaction of blood cells with the vessel walls.
The discovery of the role of nitric oxide in the human body was made by Robert F. Furchgott (hD), Louis J. Ignarro (PhD) and Ferid Murad (MD, PhD). This is one of the most important progress made in the study of cardiovascular medicine and the three were awarded the Nobel Prize in Medicine in 1998.
Nitric Oxide is a small gaseous, signaling molecule in the cardiovascular system produced by healthy endothelial cells. Signaling molecules have the function of producing another substance, the second messenger. The second messenger transmit messages along signal pathways between cells.
When NO enters a cell, it activates an enzyme called guanylate cyclase, which produces the second messenger, cyclic GMP. This second messenger relaxes and dilates the blood vessels.
So how do nitric oxide prevent strokes and cerebrovascular diseases? Nitric oxide lowers blood pressure, a high risk factor for both stroke and heart attack. By relaxing and dilating the blood vessels, it promotes healthy blood circulation to the brain and heart. It also causes coronary arteries to widen to increase blood flow to the heart.
Other roles of NO includes keeping arteries flexible, reverses arterial plaque and suppresses atherosclerosis. By preventing platelets and white blood cells from sticking to the vessel wall, NO can prevent atherosclerosis. Atherosclerosis is the accumulation of deposits of fatty wax like materials, cholesterol, calcium, waste products, and other substances along the insides of the arteries.
In addition, nitric oxide can reduce the production of free radicals, which causes blood vessels to age rapidly, and suppress abnormal growth of vascular muscle cells to prevent blood vessels from thickening.
How important is nitric oxide to our body? Nitric oxide can form biological reactions with many compounds in our body, and have been found to play a role in a number of body system processes, including immune defense, regulation of cell death (apoptosis) and neurotransmission.
Source of Nitric Oxide
L-Arginine is a semi-essential amino acid that stimulates the growth of NO within blood vessels. A semi-essential amino acid is one that can be produced by our body, or obtained from our diet.
Usually, a healthy person will have sufficient L-Arginine to produce the required amount of nitric oxide. Studies have shown that dietary supplements of L-Arginine will have little effect on people with healthy endothelium cells.
However, individuals with unhealthy endothelium cells are at risk of heart disease as their body cannot produce enough nitric oxide on their own. This is due to the presence of asymmetric dimethylarginine, a modified amino acid, that stops the production of nitric oxide. In such conditions, the human body requires dietary supplement to increase L-Arginine amounts. This will allows more NO to be produced naturally.
“… inappropriate coronary responses to sympathetic stimulation in people with coronary artery disease may be related to changes in the arginine-nitric oxide pathway and may be improved by increasing production of nitric oxide”, says Joel Cellman, M.D., of Johns Hopkins University.
Therefore, dietary supplements of L-Arginine can help prevent coronary heart diseases and CVD in high risk persons.