Protein Linked to Hypertension in Blacks

A potent protein that constricts blood vessels is four times more prevalent in African Americans with high blood pressure than in whites, says a report in this month's Hypertension. The finding suggests that genetic differences could help explain why more blacks than whites suffer from high blood pressure.

The finding is surprising because healthy blacks and whites have about the same amount of endothelin-1, a vasoconstricting chemical that is produced primarily by cells lining the inside of blood vessels. ``We weren't expecting such a big difference,'' says study leader Adviye Ergul, a molecular biologist at the University of Georgia, Athens.

Ergul's team used a new antibody test to measure endothelin levels in 100 people, half of whom suffered from high blood pressure. Besides the racial difference, the researchers found that hypertensive blacks have eight times as much endothelin as blacks with normal blood pressure. Elevated endothelin levels ``might be the reason that blacks develop hypertension earlier and develop complications from hypertension earlier'' than whites do, Ergul says.

The report is ``an interesting starting point,'' says cardiovascular epidemiologist John M. Flack of the Bowman Gray School of Medicine in Winston-Salem, North Carolina. However, he says, ``what we really need to know are the factors that influence endothelin [levels].'' Flack predicts that larger studies will reveal wide variability in endothelin levels in both blacks and whites.