1. Departments of Physiology and
2. Astra Hassle, 431 83 Molndal, Sweden;
3. Department of Surgery, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0682; and
4. Third Division of Internal Medicine, IRCCS Ospedale Maggiore, Milan, Italy 20122
5. Anesthesiology and Pain Management, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75235-9040;