As part of the proposed continuation of longitudinal studies, the hypothesis is tested that children with low-aldosterone levels are predisposed to higher blood pressures. Although Black children had lower potassium intakes, cross-sectional data indicated that only part of the racial difference in aldosterone production was secondary to a lower intake of potassium (potassium is a known stimulus of aldosterone production). Subjects with known low-aldosterone production (Blacks and whites) have diets supplemented with potassium to test the hypothesis that Blacks with low-aldosterone production have a reduced responsiveness to potassium when compared to white children with low-aldosterone. Families of children with potassium-resistant low-aldosterone production are screened for evidence of low-aldosterone production, and segregation analyses is performed to establish the mode of inheritance of the 'low-aldosterone' phenotype. In cross-sectional studies, AA-excretion rates were positively related to blood pressure in subjects greater than or equal to 10 years of age, suggesting an important role for the adrenarche in determining blood pressure levels in young people. In future longitudinal studies the role of AA as well as gonadal hormones will be studied as more children reach adolescence (the current mean age of the cohort is 12.7 yr). In addition, to better distinguish the individual influences of adrenarche, gonadarche, and increases in body size on blood pressure, a series of patients where these phenomenon are dissociated will be studied.