1. From the Center for Arrhythmia Research (V.V., X.L., M.D.), Department of Internal Medicine, University of Michigan, Ann Arbor; Zealand Pharma (B.D.L.), Glostrup, Denmark; Department of Microbiology and Immunology (W.C., S.M.T.), Upstate Medical University, State University of New York, Syracuse; and Department of Biochemistry and Molecular Biology (G.S., P.L.S.), University of Nebraska Medical Center, Omaha.