The overall goal, which is to define the underlying genetics of hypertension in an Asian population by studying intermediate phenotypes, can be divided into three parts. First, the rural Chinese population will be characterized by the collection of intermediate phenotype data on 600 unrelated individuals with high diastolic blood pressure and on 100 normotensive controls. Intermediate phenotypes include: 1) non-modulation of adrenal and renal vascular responses to angiotensin II with changes in sodium intake; 2) altered urinary kallikrein excretion; 3) low plasma renin activity response to volume depletion; 4) increased free cortisol excretion; and 5) insulin resistance. Second, candidate genes will be chosen according to the underlying physiology of the intermediate phenotypes, and variations in the coding sequences of these potentially relevant genes will be identified. Finally, polymorphisms identified in the candidate genes will be tested through case-control analyses defined by the intermediate phenotypes.