Using a model that mimics common life stressors, researchers found oestrogen 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: “Oestrogen, 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 Harshfield.
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 oestrogen levels dropped during stress and went back up afterward. “Conventional thinking tells us oestrogen 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.”
Oestrogen 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. Oestrogen 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. “We are now thinking that when black girls are under stress, they are losing all the protective effects of oestrogen,” Harshfield says.
“In whites under stress, their oestrogen levels are consistent so they are secreting vasodilators, they are blocking angiotensin and the sympathetic nervous system so the stress is not affecting them as much,” he explains. In fact, black girls in the study also showed the greatest change in angiotensin levels in response to stress, the researchers found out.
MEDICA.de; Source: Medical College of Georgia