1. From the Departments of Pharmacology (Y.F., X.H., H.Z., R.M.M., R.R.N.), Molecular and Integrative Physiology (R.M.M., L.G.D’A.), and Surgery (Vascular) (L.G.D’A.), University of Michigan, Ann Arbor; and the Department of Surgery (L.G.D’A.), William Beaumont Hospital, Royal Oak, Mich.