This project originated in response to a Request for Applications on Biobehavioral Factors Affecting Hypertension in Blacks issued in December 1982. The original project was supported by the RFA for three years. The first three years of the study focussed on the hypothesis that sodium loading would augment cardiovascular responses of psychogenic stress in Blacks at high risk for hypertension. The first phase of the study examined and compared 80 Blacks and whites, 18-22 years of age. The second phase involved an additional 40 Black borderline hypertensives who were exposed to the same set of studies designed to examine possible interactions between neurogenic and renal controlled volume mechanisms in essential hypertension.