1. Department of Physiology (C.L.B., D.M.P., C.R.S., L.P.H.), Dartmouth Medical School, Hanover, New Hampshire 03755
2. Department of Biochemistry (E.Y.B.), Dartmouth Medical School, Hanover, New Hampshire 03755
3. Department of Neurosciences (T.J.H., H.L., M.J.H.), Medical University of Ohio, Toledo, Ohio 43614