Poor Sodium Handling During Stress Linked to High Blood Pressure and Reduced Dilatation of Arteries

Newswise — For some African American youth already at-risk of high blood pressure, stressful situations may place them at even higher risk of cardiovascular disease. Mental stress-induced changes in blood pressure and sodium excretion may also affect how the blood vessels dilate to allow blood flow through the circulatory system.

In their study released today, "Impaired stress induced pressure natriuresis clusters with reduced endothelial function in African American youth at risk of hypertension," researchers Eady, Kapuku and Harshfield tested ways to identify youth at risk for deteriorating endothelial function. Endothelial dysfunction, which restricts the way the arteries dilate and allow blood flows, has been observed in patients with coronary artery disease.(1)

Fifty-two healthy African American adolescents, 15-18 years of age, participated in the study. They were given two hours of rest, one hour of stressful activity, followed by a restful recovery period of two hours. Blood pressure was taken every 15 minutes and urinary sodium excretion was assessed hourly. The researchers also assessed how well the arteries dilated during blood circulation. Known as endothelium-dependent arterial dilatation (EDAD), this function was measured using ultrasound technique.

For 31 of the youth, their response to stress showed normal sodium excretion but 21 of the youth had less sodium excretion (impaired natriuresis) than their counterparts. For those with impaired natriuresis, EDAD was lower than for those with normal natriuresis. Lower EDAD scores were linked with higher pre-stress sodium excretion, higher pre-stress diastolic blood pressure and greater increase of blood pressure during stress. In other words, higher sodium intake and higher blood pressure were associated to a reduced endothelial function, which is an early marker of cardiovascular disease.

"These results suggest that for some African American youth at-risk of high blood pressure, stress may also contribute to more rapidly declining endothelial function," stated Gaston Kapuku, MD, PhD, associate professor of pediatrics and cardiovascular scientist at Medical College of Georgia. "We will continue our study on EDAD to determine how we can address low EDAD in African American youth."

These scientific findings were presented today at the 21st International Interdisciplinary Conference on Hypertension and Related Cardiovascular Risk Factors in Ethnic Populations as Abstract 014. The abstract appears below. Additional conference information and news from the conference can be found at http://www.ishib.org/ISHIB2006.

ISHIB2006 is jointly sponsored by ISHIB and the American Society of Hypertension (ASH). ISHIB (The International Society on Hypertension in Blacks) is a nonprofit, professional medical membership organization devoted to improving the health and life expectancy of ethnic populations. ISHIB was founded in Atlanta, Georgia, in 1986 to respond to the problem of high blood pressure among ethnic populations. Each year, its international interdisciplinary conference presents advancements in the treatment and prevention of cardiovascular diseases and reducing the health disparities among ethnic minority populations. In addition to US conference locations, other sites for the conference have included Toronto, London, the US Virgin Island, Kenya, Cameroon, and Brazil.

1. Ludmer PL, Selwyn, AP, Sook TL, et al. Paradoxical vasoconstriction induced by acetylcholine in atherosclerotic coronary arteries. N Engl J Med. 1986;315:1046-1051.