1. Departments of Medicine, Physiology, Pharmacology, and Sarver Heart Center, University of Arizona, Tucson, Arizona
2. Department of Medicine and Sarver Heart Center, University of Arizona, Tucson, Arizona; Department of Cardiology, Tucson Veterans Administration Medical Center, Tucson, Arizona.
3. Department of Medicine and Sarver Heart Center, University of Arizona, Tucson, Arizona
4. Departments of Medicine, Physiology, Pharmacology, and Sarver Heart Center, University of Arizona, Tucson, Arizona; Department of Cardiology, Tucson Veterans Administration Medical Center, Tucson, Arizona.