Medetomidine

48 h after injury induction rats were anaesthetised using subcutaneous administration of 75 mg kg⁻¹ ketamine (Chanelle, Loughrea, Ireland) and 0.5 mg kg⁻¹ medetomidine (Vetoquinol, St.-Anne Lure, France). A tracheostomy was performed, and carotid artery access gained. Anaesthesia was maintained during the procedure through administrating Alfaxan IV (Jurox, Crawly, UK). Animals were mechanically ventilated and blood pressure and peak airway pressure were measured continuously. Static lung compliance and arterial blood gas analysis were measured after 20 min and repeated after 15 min of ventilation with 100% O₂. Animals were then sacrificed by exsanguination under anaesthesia.

At the time of humane killing, groups of four pigs were moved in an animal transport trailer a short distance from the home pen building to holding pens located within a nearby surgical and post-mortem facility. The pigs were weighed individually to determine the required drug dosages. For sedation, the pigs received an intramuscular injection in the neck of ketamine (5 mg/kg, Vetoquinol, Buckingham, UK), midazolam (0.5 mg/kg, Hameln, Gloucester, UK) and medetomidine (10 μg/kg, Vetoquinol) and were left undisturbed under dimmed light conditions for 10–15 min. Once each pig was sedated (i.e. immobile, absence of reaction to touch and human presence) the ear vein was catheterized. Pigs were killed humanely by injection of sodium pentobarbitone (150 mg/kg intravenously; Abbott Laboratories, Abbott Park, Illinois, USA). Death was confirmed by respiratory arrest and loss of corneal reflex. All pigs were exsanguinated by cutting the jugular and carotid arteries prior to post-mortem tissue collection.