Anaesthesia
Anaesthesia was induced in rats with sodium pentobarbitone 60 mg kg-1 intraperitoneally and, once venous access was established, maintained with intravenous boluses of 3 mg, as required. In intervention study (v), urethane was prepared as a 15% w/v solution in isotonic saline, and administered as an intraperitoneal dose of 1.4 g kg-1.
Neuroleptanalgesia was induced in rabbits by an intramuscular injection of 0.5 ml kg-1 Hypnorm (0.315 mg ml-1 fentanyl citrate and 10 mg ml-1fluanisone). Surgical anaesthesia was achieved by administering sequential 4 mg boluses of sodium pentobarbitone into the marginal ear vein, then 12 mg boluses via a cannulated femoral vein, as required, upon commencement of ventilation.