High Cholesterol and Diesel Exhaust Combine In Heart Disease
New research conducted by scientists at University of California, Los Angeles have shown that diesel exhaust can lead to exacerbated atherosclerosis, or hardening of the arteries. Small particles in air pollution combine with cholesterol to activate genes that contribute to blood vessel inflammation, which can lead to cardiovascular disease. The cumulative effects on the cardiovascular system are more than that of diesel exhaust particles or cholesterol alone.
Diesel Exhaust and Heart Disease
UCLA researchers are not the only scientists investigating the relationship between diesel exhaust and heart disease. In a recent study published in the Journal of the American Heart Association, researchers studied the effects of diesel exhaust on people during exercise. These researchers found that diesel exhaust also caused a reduction in the blood vessels' ability to expand to allow increased blood flow, as well as a reduction in the production of a chemical called tPA (tissue plasminogen activator), which helps reduce clotting.
The Research Behind It
Researchers at UCLA combined diesel exhaust particles with harmful cholesterol fats. They then added them to cultured samples of human blood vessel cells. After a few hours they isolated the DNA from the cells and found that the interaction between the exhaust particles and the cholesterol activated the gene for cellular inflammation, a major risk factor for heart disease. They duplicated their findings in living cells by experimenting on mice. Mice with high LDL cholesterol levels were exposed to diesel exhaust particles. The mice showed some of the same gene activations as the human cells. The research published in the Journal of the American Heart Association entailed exposing 30 healthy male non-smokers to fresh air and diluted diesel exhaust during intermittent exercise, and then comparing the results. The researchers found that compared to breathing fresh air, breathing polluted air while exercising was detrimental for two reasons: reduced blood flow and tPA inhibition.
Free Radicals and Atherosclerosis
Particles of air pollution, such as those in diesel exhaust, are covered with dangerous chemicals called free radicals. These free radicals are also generated by LDL cholesterol, or "bad" cholesterol, when they enter the body and metabolize. The UCLA scientists found that when combined, these two sources of free radicals actually activate the genes that cause cellular inflammation, which is a major cause of hardening of the arteries, or atherosclerosis. Atherosclerosis is a buildup of plaque in the arteries. Plaque is made up of cholesterol and other fatty substances. When plaque buildups become large, they can break off from the sides of the arterial walls, causing a blockage. This blockage is what causes a heart attack or stroke.
What is the Impact on your Health?
All this means that people who already have high LDL cholesterol levels may be more at risk for heart attack or stroke if they are exposed to air pollution. Direct exposure to diesel exhaust fumes causes the heart to be more stressed and produce less of a chemical that reduces clots than exercising in fresh air. In addition to these immediate effects, long term-exposure to diesel exhaust can harm the blood vessels by contributing to atherosclerosis and heart disease.
Heart health is very important, and proper exercise is essential to maintaining hearth health. Although there is not much one can do about exposure to air pollution, risk can be effectively reduced by lowering LDL cholesterol levels.
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