These individuals are under stress, they are holding onto salt, their blood pressure is high, it takes longer to bring their blood pressure down. That increases their cardiovascular load and can lead to premature development of essential hypertension, said the physiological psychologist at MCGs Georgia Prevention Institute.
Researchers designed a protocol that put the youths on a diet for three days to bring their sodium balance to similar levels. On test day, the youths relaxed for two hours at the Georgia Prevention Institute, were stressed for an hour by playing competitive video games, then relaxed for two more hours. Blood pressure and sodium excretion were checked throughout the five-hour protocol.
Two-thirds of participants showed a normal response, with blood pressure and sodium conservation increasing during stress and decreasing afterward. But one-third had decreased sodium excretion during stress, which increased their blood volume and pressure and kept it up during the recovery period.
(T)he results of this study provide support for our hypothesis that stress-induced impaired pressure natriuresis leads to an extended period of elevated blood pressure, Dr. Harshfield said in his presentation. As such, this study provides evidence for an alternative hypothesis to the traditional reactivity hypothesis to explain the causative role of stress in the development of essential hypertension. This hypothesis is particularly appealing for the black population whose blood pressure is more sensitive to the effects of sodium.
Sodium is involved in all nervous system regulation, physiologic functions and fluid volumes, he said. The body doesnt produce sodium but tightly regulates its levels through a number of mechanisms. These include angiotensin 2, a vasoconstrictor that also directs the kidneys to reabsorb salt. Additionally, angiotensin 2 stimulates aldosterone, a hormone produced by the
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Contact: Toni Baker
tbaker@mail.mcg.edu
706-721-4421
Medical College of Georgia
16-May-2002