1. From the Department of Internal Medicine, Divisions of Nephrology and Hypertension (X.-Y.Z., A.R.C., L.O.L.) and Cardiovascular Diseases (M.R.P., A.L., L.O.L.), and the Department of Physiology and Biomedical Engineering (E.L.R.), Mayo Clinic, Rochester, Minn, and the Department of Biological Sciences (M.D.B.), Minnesota State University, Mankato, Minn.