1. From the Department of Physiology, University Maastricht, Maastricht, The Netherlands (J.E., S.Z., D.L., B.M., S.V., A.v.H., M.A.A., U.S.); Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands (H.C.); and Department of Medicine, University Hospital Basel, Basel, Switzerland (J.E.).