1. From the Divisions of Cardiology (I.F., A.E.G.) and Clinical Pharmacology (S.R., I.B.), Departments of Medicine (I.F., A.E.G., S.R., I.B.) and Pharmacology (I.F., I.B.), Vanderbilt University, Nashville, Tenn; CV Therapeutics (D.Z., L.B.), Palo Alto, Calif; and the Department of Pharmacology (T.V.-Y.), University of Illinois, Chicago, Ill.