1. From the Departments of Internal Medicine (K.G.L., D.X., J.M.), Pharmacology (K.G.L.), and Anatomy and Cell Biology (W.Z., L.P.C., R.J.T.), and the Cardiovascular Center (K.G.L., W.Z., D.X., L.P.C., J.M., R.J.T.), University of Iowa, Roy J. and Lucille A. Carver College of Medicine, Iowa City; and the Department of Veterans Affairs (K.G.L., D.X., J.M.), Iowa City, Iowa.