One third of the 118 black males and females age 15 to 18 in the Medical College of Georgia study had an impaired ability to eliminate sodium in their urine hours after the stress subsided, according to the study presented May 16 at the 17th Annual Scientific Session of the American Society of Hypertension in New York.

The body naturally increases blood pressure during stress, immediately by constricting blood vessels and longer term by directing the kidneys to retain more sodium and so increase blood volume, said Dr. Gregory A. Harshfield, first author on the presentation, Impaired Stress-Induced Pressure Natriuresis Increases Cardiovascular Load in Black Youths.

Many previous studies looking at why blacks are at increased risk for hypertension have supported the hypothesis that they have an exaggerated response to stress, Dr. Harshfield said. However the physiologic response to stress is dynamic and includes both the response to the stress per se and the changes that restore blood pressure to pre-stress levels, he said in his presentation.

His study showed one mechanism key to restoring blood pressure natriuresis or secreting sodium in the urine is impaired in some black youths with normal blood pressures. As such, we hypothesize that the interaction between salt and stress is more important than either of the factors considered separately, he wrote.

This says to me that the stresses of the day are affecting these individuals differently in that they are affecting their long-term blood pressure control system, Dr. Harshfield said, noting his previous work at Charles R. Drew University in California which showed that the blood pressure of blacks doesnt drop, even when s
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Contact: Toni Baker
tbaker@mail.mcg.edu
706-721-4421
Medical College of Georgia
16-May-2002