The first subproject studied cardiac output, systemic vascular resistance, echocardiographic dimensions, responses to exercise and to mental stress in these groups of children. The purpose of this study was to define whether there were significant differences in blood pressure control during rest, exercise and mental stress in these groups and to determine whether differences in left ventricular wall mass resulted in these groups. The second subproject studied blood pressure control mechanisms in a free-living sample of these five groups while they consumed usual, high and low salt diets. Measurements were made of baroreflex control, structural component of vascular resistance, and response to mental stress. The purpose of this study was to define whether salt sensitivity existed in school children and how it expressed itself on blood pressure control mechanisms.