Department of Medicine, Division of Nephrology, University of Groningen, University Medical Center Groningen, The Netherlands. Department of Medicine, Division of Vascular Medicine and Pharmacology, Erasmus Medical Center, Rotterdam, The Netherlands. Department of Clinical Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands. General Practitioner Practice Gorecht, Hoogezand, The Netherlands. General Practitioner Practice Boterdiep, Groningen, The Netherlands. Department of Pharmacology, Kagawa University, School of Medicine, Miki, Kita District, Kagawa, Japan. Department of Internal Medicine, Division of Nephrology, ZGT Hospital Almelo, Netherlands.