1. From the Department of Molecular Physiology and Biophysics (E.B., D.M.), University of Vermont Medical School, Burlington, Vt; Department of Medicine (C.S.), Brigham and Women’s Hospital, and Howard Hughes Institute and Department of Genetics (J.G.S.), Harvard Medical School, Boston, Mass; and Cardiology Unit (M.L.), University of Vermont Medical School, Burlington, Vt.