Fig. 2.

Design of short-term experiments. Animals were randomized to either nalbuphine or placebo (NaCl 0.9%) infusions. OP operation (=instrumentation). The subcutaneous administration of nalbuphine in combination with lidocaine was requested by the animal ethics committee in order to avoid post-operative pain after termination of isoflurane anaesthesia. Placebo animals received a subcutaneous injection of normal saline (2 ml/kg)