According to the report, antioxidants and L-arginine, an amino acid,
protected the cells of human blood vessels from the wear and tear of fluid
rushing by.
Branch points, areas where two vessels meet, are particularly vulnerable
because they are exposed to turbulent shear-stress, a type of force imposed by
the flow of blood that can cause inflammation and plaque build up leading to
atherosclerosis, or hardening of the arteries.
Shear-stress can also increase damage from free radicals, compounds that can
cause varying degrees of damage to cells, researchers report in the online early
edition of the Proceedings of the National Academy of Sciences (news
- web
sites).
To investigate if antioxidants and L-arginine might prevent this type of
damage, researchers exposed human cells to different fluid flow forces inside a
culture dish.
High shear-stress caused cells to produce inflammatory compounds. However,
fewer dangerous compounds were produced when cells were coated with antioxidants
and L-arginine. These substances also caused the cells to produce eNOS
(endothelial nitric oxide synthase), an enzyme that allows vessels to expand and
prevents blood from clotting.
Antioxidants have been shown to squelch free radicals while L-arginine is a
precursor of nitric oxide, a compound that helps the inner lining of blood
vessels to dilate.
In a second experiment, researchers demonstrated that these compounds reduced
the damage caused by shear-stress in mice bred to have high cholesterol.
"These results demonstrate that atherogenic effects induced by turbulent
shear-stress can be prevented by co-treatment with antioxidants and L-arginine,"
Dr. Louis J. Ignarro from the University of California in Los Angeles and
colleagues conclude.
