1. From the Departments of Anesthesia (W-S.C., S.C., D.S., T.J.B., S.K.), Neurology (G.B.R.), Molecular Physiology and Biophysics (G.B.R.), and Pharmacology (T.J.B.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.