1. From the Sarver Molecular Cardiovascular Research Program, Departments of Physiology and Cellular and Molecular Medicine, University of Arizona, Tucson, AZ (M.M., K.R.H., E.-J.L., J.E.S., C.S., C.G.H., C.A.C.O., H.G.); and Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands (C.A.C.O.).