1. From the Medical Faculty, Department of Cardiovascular Physiology, Heinrich-Heine-University, Düsseldorf, Germany (A.-E.H., C.A., S.K., M.I., S.S., S.B., M.K.)
2. Department of Systems Physiology, Ruhr-University Bochum, Germany (K.U., N.H.)
3. Department of Cardiovascular Surgery, University Clinic Bonn, Germany (W.R.)
4. Bayer AG, Drug Discovery, Pharmaceuticals, Wuppertal, Germany (F.D., N.S.)
5. Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, University of Antwerp, Belgium (L.V., G.W.D.)
6. Institute of Physiology II, University of Munster, Germany (W.A.L.).