Glutamate uptake is not a major target site for anaesthetic agents

Abstract

We have examined the effects of thiopentone, propofol and ketamine 3-300 μmol litre-1, 3.6%, 2.4 rat MAC of isoflurane, 3.0%, 2.4 rat MAC of halothane and morphine 0.1-10 μmol litre-1 on uptake of [3H]glutamate into rat cerebrocortical and cerebellar synaptosomes. Corticol and cerebellar synaptosomes took up [3H]glutamate in a time-, concentration-, Na+-dependent and L-trans-pyrrolidine-2,4-dicarboxylate inhibitory manner. The K(m) and Vmax values for uptake were 8.6 μmol litre-1 and 1.7 nmol/min/mg protein and 2.2 μmol 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.