Saturday, August 4, 2012

Damage to Blood Capillaries in Diabetes

Capillary Problems and Blood Glucose

When a capillary narrows the flow decreases dramatically. If you halve the radius of a blood capillary the blood flow through the capillary decreases to one-sixteenth of its normal rate. 

This will cause an increase in blood pressure (think hypertension) which can lead to ruptured blood vessels. In the brain region, a stroke is possible. Heart attacks can occur with lessened blood flow to the arteries that supply the heart muscle.

Blood vessels capillary networks in diabetics are unable to relax well. Researchers believe  altered proteins involved in relaxation are affected by a glucose-derived molecule. The net result is possible hypertension, chance of strokes and increased obesity.

When insulin is not present in the circulatory system the level of glucose remains high in our circulatory system. It begins to decrease the level of nitric oxide, a chemical that increases the diameter of blood vessels. The continual exposure to high blood glucose levels leads to the eventual narrowing of the blood vessel system.

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Unfortunately, in diabetes, when a person has their diabetes under control, a small percentage of the glucose is converted to a sugar type that can modify the proteins.

In your blood vessels this modified glucose competes with a mechanism called phosphorylation that modifies an enzyme that makes possible the formation of  nitric oxide. Its name tells you what it does. Its called a nitric oxide synthase. It catalyzes the formation of nitric oxide, a blood vessel dialator. The modified-glucose wins out in the competition with phosphorylation and negates the formation of nitric oxide. Net result is constricted blood vessels that increase a diabetics chance for developing high blood pressure, strokes and heart attacks.

Researchers are focusing on blocking the mechanism that prevents the formation of the modified-glucose molecule. If that is successful the effect on nitric oxide production will cease and become normal and the danger from hypertension, stroke and heart attacks will diminish.

Interesting point to remember about nitric oxide is the nitro glycerine tablet a person takes to dilate their heart blood vessels in a heart attack. 

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