The first physical explanation of why blacks are prone to high blood pressure, cardiovascular disease and strokes has been announced by researchers who say the findings may open the door to the development of new treatments.
University of Georgia scientists found that arteries from black patients with severe heart disease were unable to return quickly to normal size after they had constricted in response to stress or medications. This relaxation is impaired, they found, because cells lining the arteries do not produce chemicals that stimulate enlargement.
The sustained constriction increases blood pressure, places extra stress on the heart, and increases the risk of a vessel rupturing, Dr. Randall Tackett said yesterday at the Ninth International Interdisciplinary Conference on Hypertension in Blacks, held in Cleveland.
Blacks have a 27 percent higher death rate from heart disease than whites and are twice as likely to die from stroke.
Dr. Tackett's team made the discovery using leftover artery tissue from heart bypass recipients to test the arteries' ability to relax. Similar, as-yet-unreported results from a team in New York that used a different technique support his findings, suggesting that researchers may be well along the road to explaining the high rate of hypertension and related diseases in blacks.
As a result of Dr. Tackett's findings, the researchers say that they will be able to test and develop medications to see which are most effective for blacks. Understanding the mechanism should make it possible to design new agents targeted at black hypertension, they added.
"This is a tantalizing, extremely interesting finding whose significance is in its promise [for drug development]," said Dr. Stevo Julius of the University of Michigan.
Some researchers have suggested that the susceptibility of blacks to the disorders is socioeconomic and cultural, reflecting lack of access to physicians, failure to take prescribed medicine and similar factors.