To determine the effect of inhalation anaesthetics on the plasma concentration of laudanosine necessary to produce CNS excitation, we administered laudanosine 0.5 mg kg-1 min-1 i.v. to 40 rabbits under eight study conditions: 1.0 or 0.7% halothane, 1.6% isoflurane, 2.0% enflurane, during normocapnia