KETAMINE FAILS TO PROTECT AGAINST ISCHAEMIC NEURONAL NECROSIS IN THE RAT

Ketamine is a dissociative anaesthetic known to be an NmethylD aspartate receptor blocker. Since the NMDA excitatory receptoron neurones is implicated in ischaemic neuronal necrosis, ketaminemight be expected to have a beneficial effect in cerebral hypoxia-ischaemia.Ketamine was tested in a rat model of forebrain ischaemia allowing7 days recovery. Ketamine 6mg kg^–1 i.v. was administered5–10 min before ischaemia in one group of rats, and ketamine60mg kg^–1 day^–1 i.m. for 3 days and 7 continuousdays after ischaemia in two other groups. An additional groupreceived ketamine 24 mg kg^–1 i.v. before ischaemia and120 mg kg^–1 day^–1 i.m. after ischaemia for 7 dayscontinuously. Control rats received ischaemia but no treatment.The results were compared with untreated controls by neuropathologicalexamination of the entire brain, sectioned subserially. Therewas no significant difference in necrosis between treated anduntreated groups after any of the ketamine regimens. The findingsdemonstrate that systemically administered ketamine fails toprotect the brain against hypoxic-ischaemic injury in the rat.