1. From the Departments of Cardiology1 and Nephrology,2Ullevaal University Hospital, Oslo, Norway; the Departments of Clinical Physiology and Nuclear Medicine3 and Internal Medicine,4Glostrup University Hospital, Glostrup, Denmark; Merck Research Laboratories, Blue Bell, PA;5 and the Division of Hypertension, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI6