High blood pressure also called hypertension is a major health problem that when left untreated can lead to heart disease, stroke and kidney failure. African Americans are more likely to develop high blood pressure and develop it earlier in life than Caucasians. But the reasons for the heightened risk in African Americans still remained largely unknown, although new evidence may provide some insight.
Dr. TanYa Gwathmey from the Hypertension and Vascular Research Center of Wake Forest University Baptist Medical Center studies the factors that contribute to having high blood pressure, particularly in African Americans. Her group found that there are racial differences in the activity of enzymes that make or breakdown a major regulator of blood pressure. And her results correlate with the bias of African Americans being more at risk.
At the annual 2010 Experimental Biology conference in Anaheim, CA held April 24-28 (http://experimentalbiology.org/content/default.aspx), Gwathmey will be discussing these findings in her presentation titled "Sex and Racial Background Influence Angiotensin Peptide Metabolism in Young Adults." The team of researchers that also contributed to this study includes Hossam Shaltout and Mark Chappell of the Hypertension and Vascular Research Center; James Rose of the Center for Perinatal Research; Lisa Washburn of the Department of Pediatrics from the Wake Forest University Baptist Medical Center; and Patricia Nixon of the Department of Health and Exercise Science of Wake Forest University, Winston-Salem, NC.
Two Peptides With Opposing Function Blood pressure is regulated by peptides (short strings of amino acids) called angiotensins. Specific forms of angiotensin affect blood pressure differently. Angiotensin II causes the body to retain salt and water and causes blood vessels to constrict; all characteristics that 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 not be as likely to develop high blood pressure.
High Risk Individuals Have Differences In Angiotensin Hormone Metabolism During adolescence, most individuals haven't developed high blood pressure yet. Gwathmey chose to study participants at age 15 to identify predicting factors of high blood pressure that may be present before the disease has set in. Gwathmey's study specifically 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.