1. Department of Physiology and Biophysics, Mississippi Center for Heart Research, University of Mississippi Medical Center, Jackson, Mississippi
2. Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, Jackson, Mississippi
3. Department of Physiology, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
4. Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
5. Cardiac Ultrasound Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania