Understanding hypertension in African Americans prov...( Exercise cannot reduce a sodium-reta...)

Exercise cannot reduce a sodium-retaining hormone in African Americans known to potentially cause hypertension, found Michael D. Brown, Ph.D., the senior author of a study in the September issue of Experimental Physiology. Brown is an associate professor of kinesiology at Temple Universitys College of Health Professions.

The hormone, aldosterone, influences the kidneys regulation of blood pressure, but too much of it can contribute to the development of hypertension because it causes the kidney to retain salt. Aldosterone, released by the adrenal glands on top of the kidneys, plays a role in the complex system used by the body to regulate blood pressure.

Although the results are discouraging for African Americans and hypertension, itll point us in other directions that may have more potential and could be the key to reducing hypertension, said Brown, who has a background in exercise physiology.

Many African Americans develop the salt-sensitive form of hypertension. Approximately 40 percent of African Americans have hypertension the highest rate of any racial or ethnic group in the United States but there is little data about what makes them more susceptible to this condition, Brown said.

This study is based on the premise that the prevalence of blood pressure sensitivity to salt is extremely high is African Americans. Alterations in aldosterone regulation may play a role because aldosterone causes the kidney to retain salt. Brown said he wanted to find out if exercise could lower the levels.

In the study, he found that the level of aldosterone was related to how the two racial groups distributed body fat. Caucasians generally stored fat in the abdomen area, whereas African Americans had fat distributed throughout the body in a layer under the skin. The six-month study involving 35 Caucasians and African Americans with hypertension found that aerobic exercise training program reduced aldosterone levels in Cauc
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