Note: This UCSD GCRC protocol utilized the UVA GCRC VAX computer for continued access to CLINFO software for data analysis. This study examines the effect of salt and stress on blood pressure regulation with particular emphasis on the sympathetic nervous system and the renin angiotensin system. Patients are studied on a low-salt diet (10 mEq. sodium/day) during 2 hospitalizations where they receive, in a double-blind fashion, either placebo or an angiotensin-converting enzyme inhibitor.