1. School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
2. Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, Heidelberg D-69120, Germany.
3. Department of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, Saarland University, Homburg D-66424, Germany.
4. Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, UK.
5. Transmembrane Signaling Group, National Institutes of Health, Research Triangle Park, NC 27709, USA.