Using a model that mimics common life stressors, researchers found estrogen levels drop during stress in healthy black girls but remain consistent in whites, said Dr. Gregory Harshfield, director of the Medical College of Georgia's Georgia Prevention Institute.
"Estrogen, which helps blood vessels dilate, is good for your blood vessels and if you lose that protection during periods of stress in the day it may contribute to the early development of heart disease we typically see in black women," says Dr. Harshfield.
Research being presented during the 21st Annual International Interdisciplinary Conference on Hypertension and Related Cardiovascular Risk Factors in Ethnic Populations in Atlanta June 23-26 looked at 48 mostly female teens with normal blood pressure.
Researchers found the greatest changes in blood pressure response to stress in black girls and blood samples taken before, during and one hour after playing a competitive video game showed their estrogen levels dropped during stress and went back up afterward.
"Conventional thinking tells us estrogen is not normally a major player in regulating blood pressure during stress," says Dr. Harshfield. "This tells us sex hormones do play a role in regulating blood pressure but, unfortunately, it's a bad one in black females."
Estrogen influences blood pressure by releasing nitric oxide, a vasodilator, and by blunting the response of the sympathetic nervous system the fight or flight response as well as angiotensin II, a vasodilator. Estrogen is believed to be one of the main reasons women have lower rates of heart disease than men until after menopause, says Martha Castles, research manager, who is presenting the research.