1. From the Department of Pharmacology (K.S., C.-C.W., J.C., K.G., K.I., M.L.S.), New York Medical College, Valhalla, NY; Department of Biochemistry (M.G., J.R.F.), University of Texas Southwestern Medical Center, Dallas, Tex; Department of Physiology and Pharmacology (N.G.A.), University of Toledo, Toledo, Ohio.