1. Dipartimento di Scienze Farmaceutiche, Università di Ferrara, 44100 Ferrara, Italy, Nicox Research Institute, Via Ariosto 21, 20091 Bresso, Milan, Italy, and The William Harvey Research Institute, Pharmacology Division of St. Bartholomew's & The Royal London School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, United Kingdom