1. Department of Pharmacology and Toxicology (C.A.N., G.D.F., H.G., J.R.H., E.L.L.-T., J.L.M., P.W.P., A.M.D.), Michigan State University, East Lansing, Michigan 48824
2. Department of Physiology (W.E.R., C.S.R.), Medical College of Georgia, Augusta, Georgia 30912