Glutamate uptake is not a major target site for anaesthetic agents.
We have examined the effects of thiopentone, propofol and ketamine 3-300 mumol litre-1, 3.6%, 2.4 rat MAC of isoflurane, 3.0%, 2.4 rat MAC of halothane and morphine 0.1-10 mumol 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-transpyrrolidine-2,4-dicarboxylate inhibitory manner. The Km and Vmax values for uptake were 8.6 mumol litre-1 and 1.7 nmol/min/mg protein and 2.2 mumol 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.
Nicol
B
B
University Department of Anaesthesia, Leicester Royal Infirmary.
Rowbotham
D J
DJ
Lambert
D G
DG
D000778:Anesthetics, Dissociative / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D007700:Kinetics; D009020:Morphine / Q000494:pharmacology*; D015742:Propofol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism; D013874:Thiopental / Q000494:pharmacology
D000778:Anesthetics, Dissociative; D018686:Anesthetics, Intravenous; D018698:Glutamic Acid; D009020:Morphine; D013874:Thiopental; D015742:Propofol