Fig. 1. Schematic illustration of the experimental protocol. Three separate treatment trials were performed. The volunteers received propofol (at a target concentration of 2.0 μg/ml), 10% Intralipid® (Fresenius Kabi, Stans, Switzerland) (corresponding to a target-controlled infusion of propofol with a concentration level of 2.0 μg/ml), or saline as a control. The drugs were delivered during 45 min, starting 30 min after the onset of electrical stimulation. Continuous pain and areas of punctate hyperalgesia and allodynia were determined repeatedly.