Factors of hormone metabolism may make African Americans more likely than Caucasians to develop high blood pressure and to develop it earlier in life. Left untreated, high blood pressure, or hypertension, can lead to heart disease, stroke and kidney failure.
Dr. TanYa Gwathmey from the Hypertension and Vascular Research Center of Wake Forest University Baptist Medical Center studied the factors that contribute to hypertension, particularly among African Americans. She and her colleagues found racial differences in the activity of enzymes that make or break down a major regulator of blood pressure, and their results confirm that African Americans are more at risk.
Blood pressure is regulated by peptides (short strings of amino acids) called angiotensins. Angiotensin II causes the body to retain salt and water and causes blood vessels to constrict – all of which promote high blood pressure.
On the other hand, angiotensin (1-7) has protective effects against high blood pressure by causing blood vessels to open up and allowing the body to release salt and water.
The enzyme ACE (angiotensin converting enzyme) makes the riskier angiotensin II. But angiotensin II can be converted to the protective angiotensin (1-7) by the enzyme ACE2. So someone with high ACE activity would make more angiotensin II and would be more at risk for high blood pressure. Alternatively, someone with higher ACE2 activity would make more angiotensin (1-7) and would be less likely to develop high blood pressure.
In angiotensin hormone metabolism during adolescence, most individuals haven’t developed high blood pressure yet. Gwathmey studied participants at age 15 to identify predicting factors of high blood pressure present before the disease has set in. Gwathmey’s study examined African American boys and girls and Caucasian girls. All participants tested had normal blood pressure. Urine samples were collected from the participants and analyzed for levels of ACE and ACE2 enzymes as a read-out for the predominant form of angiotensin.
African American boys had higher ACE levels than both African American and Caucasian girls, meaning the African American boys may have higher levels of angiotensin II. Researchers also observed that African American girls had less ACE2 than Caucasian girls, meaning they may make less of the protective angiotensin (1-7) hormone.
“What is really interesting to me is that we are seeing changes in angiotensin metabolism before blood pressure changes,” Gwathmey was quoted as saying. “This could become a useful tool for predicting high pressure and potential therapeutic treatment before hypertension actually sets in.”
“We can’t group all people into one category to assess the blood pressure system,” said Gwathmey. “If we look at a study without consideration of racial and/or gender influences, then we may be missing out on key information that may better help us to address this epidemic.”
SOURCE: Presented at the Experimental Biology conference, Anaheim, CA, April 24-28, 2010.