1. From the Divisions of Cardiovascular Research (R.J.D., M.B., A.H., G.J.W.) and Pathology (G.J.W.), Research Institute, The Hospital for Sick Children; the Departments of Physiology (H.C.C., M.B., P.H.B., G.J.W.) and Medicine (P.H.B.), The University of Toronto; and the Division of Cardiology (C. Z., P.H.B.), University Health Network, Toronto, Canada. Present address of C.Z. is Laboratory of Muscle Research and Molecular Cardiology, Clinic III for Internal Medicine, University of Cologne, Cologne,...