1. From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee.