At T=0, metoprolol intravenous solution (0.5 mg metoprolol/ml as metoprolol tartrate) or placebo is administered as an intravenous bolus injection. Continuous infusion of metoprolol/placebo is then administered until T=30 minutes. Infusion is halted if heart rate drops below 35 bpm or systolic blood pressure drops below 80 mm Hg, or the participant experiences subjective side effects. Infusion stops at T=30 minutes. Intravenous lipid emulsion (Intralipid 20 %) or saline solution is shortly thereafter administered as an intravenous bolus infusion (1.5 ml/kg) followed by a continuous infusion (infusion rate: 0.25 ml/kg/min). Lipid emulsion/dummy infusion is stopped at T = 30 minutes. One gram of paracetamol administered as a disintegrating tablet dissolved in 50 ml of water is given per os shortly before study start on each day.