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Fall 1998

Research Magazine > ARCHIVE > Spring 98 > Article

Radical Differences
by Judy Bolyard Purdy

A recent UGA study may help explain why African-American men have a much higher incidence of heart disease than Caucasian men.

Randall Tackett, a professor of clinical and administrative sciences in the UGA College of Pharmacy, has studied the differences between blood vessels of African Americans and Caucasians since 1992.

His latest study of saphenous vein tissue (a vein in the leg) from male heart bypass patients suggests that blood vessels from African Americans generate almost twice as many free radicals as those from Caucasians. It also may suggest that antioxidants — vitamins C and E and other compounds that scavenge free radicals — have a beneficial role in therapy.

"The body produces free radicals, which are highly reactive molecules that circulate in the bloodstream and can attack and damage body tissues such as the blood vessels," said Tackett, the study’s lead researcher. "Some free radicals, including one called superoxide, have been shown to interfere with the ability of blood vessels to vasodilate, or relax.

"Free radicals also may play a role in the development of plaques that occur in atherosclerosis, or hardening of the arteries, by attacking the blood vessel walls, damaging them so they can’t relax," Tackett said.

African-American men have a 27 percent higher death rate from cardiovascular disease than do Caucasian men. They also have a higher incidence of high blood pressure, coronary artery disease and diabetes. Tackett’s team, which includes Lionel Zumbro of University Hospital, Augusta, Ga.; Joe Rubin of the Medical College of Georgia, Augusta; UGA technician Cynthia Lane; graduate student LiFan Zhao; and research apprentice Vija Fleming, is trying to find out why.

Their study, sponsored in part by the Georgia affiliate of the American Heart Association, measured production of superoxide in saphenous vein segments of 18 African Americans and 26 Caucasians. They found nearly twice as much in African Americans’ veins. Although other research has demonstrated that free radicals are involved in cardiovascular diseases, this was the first study to measure production of free radicals in African Americans.

The researchers also measured the levels of enzymes that scavenge free radicals to determine if these levels were different between the two groups. Both groups had the same enzyme levels, so the researchers concluded that African Americans’ defense system is not enhanced to scavenge their higher free radical production.

The team also looked to see if the higher level of superoxide was involved in the decreased ability of African-Americans’ veins to dilate. They observed an improved ability of vein segments to relax in the presence of antioxidant compounds.

These findings complement the team’s earlier findings, widely reported in 1994, that racial differences exist in blood vessels. The earlier studies showed that blood vessels from African Americans had a reduced ability to dilate because of a lack of nitric oxide, a substance produced by the cells that line blood vessels. Since superoxide can inactivate nitric oxide, increased production of superoxide could help explain the veins’ reduced capacity to relax.

"No other studies have been done on this minority population, which has a high incidence of cardiovascular disease," Tackett said. "We already know the important role antioxidants like vitamin E play in some cancers and other diseases. Clinical studies suggest that these same anitoxidants may also help prevent the onset of cardiovascular diseases. And that’s an economically viable option."

For more information, contact Randall Tackett at rtackett@rx.uga.edu


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