1. Departments of Physiology and Pharmacology (R.L.G., S.M.H., C.C.N., B.W., A.S.T.), Robert C. Byrd Health Sciences Center, Morgantown, West Virginia 26506
2. Department of Anatomy and Cell Biology (M.J.M.), Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1
3. Mammal Research Institute (R.P.M.), University of Pretoria, Pretoria 0002, South Africa
4. University of Capetown/Medical Research Council Receptor Biology Unit (R.P.M.), University of Cape Town, 7701 Cape Town, South Africa
5. Centre for Integrative Physiology (R.P.M.), University of Edinburgh, Edinburgh EH16 4SB, Scotland, United Kingdom
6. Department of Molecular and Integrative Physiology (L.M.C., M.N.L.), University of Michigan, Ann Arbor, Michigan 48109