Before any surgical procedure were performed, all the pigs were pretreated with atropine (Polfa, Poland, 0.04 mg/kg b.w., s.c.) and propionylpromasine (Stresnil, Janssen Pharmaceutica, Belgium, 0.5 mg/kg b.w., i.m.), and after 30 min, the main anaesthetic drug, sodium pentobarbital (Tiopental, 0.5 g per animal), was given intravenously in a slow fractionated infusion.