GLUTAMATE UPTAKE IS NOT A MAJOR TARGET SITE FOR ANESTHETIC AGENTS

We have examined the effects of thiopentone, propofol and ketamine 3-300 mu mol litre(-1), 3.6%, 2.4 rat MAC of isoflurane, 3.0%, 2.4 rat MAC of halothane and morphine 0.1-1O mu mol litre(-1) on uptake of [H-3]glutamate into rat cerebrocortical and cerebellar synaptosomes. Corticol and cerebellar synaptosomes took up [H-3]glutamate in a time-, concentration-, Na+-dependent and L-trans-pyrrolidine-2,4-dicarboxylate inhibitory manner. The K-m and V-max values for uptake were 8.6 mu mol litre(-1) and 1.7 nmol/min/mg protein and 2.2 mu mol litre(-1) and 0.7 nmol/min/mg protein in cortical and cerebellar preparations, respectively. At clinically relevant concentrations none of the agents tested influenced the uptake process. Our data suggest that the uptake of glutamate is not a major target site for anaesthetic or analgesic agents.