BEHAVIORAL STRESS AND SODIUM REGULATION IN YOUTHS

DESCRIPTION (adapted from investigator's abstract): Cardiovascular disease remains the leading cause of death. Race and obesity are two of the leading risk factors for cardiovascular disease and essential hypertension. These two groups are characterized by impaired sodium regulation, such that they are very sensitive to the effects of changes in sodium intake. It has been hypothesized that psychological stress might contribute to the hypertensive process by inducing a period of sodium retention and thereby increasing the duration blood pressure remains elevated following the cessation of the stressor. This hypothesis will be tested by measuring changes in sodium excretion 2 hours before and 2 hours following a 1 hour stress period in two groups of subjects, obese and non obese blacks, with the hypothesis that obese subjects will continue to retain sodium following stress. Furthermore, changes in the activity of hormonal variables known to influence sodium handling will be measured, with the hypothesis that the mechanism underlying the patterns will differ between the two groups specifically, the insulin regulatory system will be the primary hormone driving the response pattern in the obese individuals, and the sympathetic nervous system in non-obese subjects. Finally, the groups will differ in hemodynamic profiles, with the obese subjects continuing to show an increase in cardiac output and blood pressure following the cessation of the stressor. This study will provide new information on how psychological factors contribute to the development of CVD in blacks, particularly obese blacks. In so doing, it will help clarify the role that stress-induced changes in other hormones, both alone and in conjunction contribute to the pathological increase in sodium reabsorption. It will also define the hemodynamic response pattern associated with these changes. Finally, this study will examine these questions in a younger cohort than has been studied previously, providing new information on this population.