1. From the Department of Physiology, Cardiovascular Center, Medical College of Wisconsin, Milwaukee (J.W., S.F., K.-T.L., K.W., J.L.G., C.D.S.)
2. Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa (S.F.)
3. Department of Pharmacology, New York Medical College School of Medicine, Valhalla (M.L.S.)
4. Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (S.D.).