Researchers at The Medical College of Wisconsin in Milwaukee have linked higher levels of the hormone aldosterone to high blood pressure and blood vessel disease in African Americans. Aldosterone is secreted by the adrenal glands and causes salt retention by the kidneys.
The study appeared in the December 18, 2008, American Journal of Hypertension.
"The prevalence of high blood pressure, or hypertension, in African Americans is among the highest in the world," says lead researcher Theodore Kotchen, M.D., professor of medicine and associate dean for clinical research.
"Previously, we found relatively high aldosterone levels in African Americans with high blood pressure," he said. "In this study we have found that aldosterone may not only contribute to high blood pressure but also to related changes in blood vessel function in the kidneys and extremities."
The researchers compared 24-hour blood pressures, heart output, blood vessel stiffness, kidney blood flow, and aldosterone levels in 224 African Americans with high blood pressure, with those of 217 African Americans with normal blood pressure.
They found that those with high blood pressure had higher levels of aldosterone. Their heart output was lower, extremity blood vessel stiffness was greater, kidney blood flow was lower, and kidney resistance to blood flow was higher than those with normal blood pressure.
Most importantly, the blood pressure levels, blood vessel flexibility, and kidney blood flow in those with high blood pressure were all directly correlated with their aldosterone levels.
"These observations suggest that aldosterone contributes to high blood pressure and its related heart, kidney, and blood vessel disease in African Americans," says Dr. Kotchen.
His research has been continuously funded by the National Institutes of Health's National Heart, Lung and Blood Institute for over a decade.
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