1. Department of Physiology and Cell Biology; College of Medicine; and Davis Heart and Lung Research Institute; The Ohio State University; Columbus OH 43210 USA
2. Center for Arrhythmia Research; Cardiovascular Division of the Department of Internal Medicine; University of Michigan; Ann Arbor MI 48109 USA
3. Division of Clinical Pharmacology; Vanderbilt University Medical School; Nashville TN 37232 USA