|Title||Reduced inhibition of cortical glutamate and GABA release by halothane in mice lacking the K+ channel, TREK-1.|
|Publication Type||Journal Article|
|Year of Publication||2007|
|Authors||Westphalen RI, Krivitski M, Amarosa A, Guy N, Hemmings HC|
|Journal||Br J Pharmacol|
|Date Published||2007 Nov|
|Keywords||Anesthetics, Inhalation, Anesthetics, Local, Animals, Blotting, Western, Brain Chemistry, Cerebral Cortex, gamma-Aminobutyric Acid, Glutamic Acid, Halothane, Immunohistochemistry, Mice, Mice, Inbred C57BL, Mice, Knockout, Nerve Endings, Neurotransmitter Agents, Potassium Channels, Tandem Pore Domain, Pulmonary Alveoli, Receptors, Presynaptic, Synaptosomes, Tetrodotoxin|
BACKGROUND AND PURPOSE: Deletion of TREK-1, a two-pore domain K(+) channel (K(2P)) activated by volatile anaesthetics, reduces volatile anaesthetic potency in mice, consistent with a role for TREK-1 as an anaesthetic target. We used TREK-1 knockout mice to examine the presynaptic function of TREK-1 in transmitter release and its role in the selective inhibition of glutamate vs GABA release by volatile anaesthetics.
EXPERIMENTAL APPROACH: The effects of halothane on 4-aminopyridine-evoked and basal [(3)H]glutamate and [(14)C]GABA release from cerebrocortical nerve terminals isolated from TREK-1 knockout (KO) and littermate wild-type (WT) mice were compared. TREK-1 was quantified by immunoblotting of nerve terminal preparations.
KEY RESULTS: Deletion of TREK-1 significantly reduced the potency of halothane inhibition of 4-aminopyridine-evoked release of both glutamate and GABA without affecting control evoked release or the selective inhibition of glutamate vs GABA release. TREK-1 deletion also reduced halothane inhibition of basal glutamate release, but did not affect basal GABA release.
CONCLUSIONS AND IMPLICATIONS: The reduced sensitivity of glutamate and GABA release to inhibition by halothane in TREK-1 KO nerve terminals correlates with the reduced anaesthetic potency of halothane in TREK-1 KO mice observed in vivo. A presynaptic role for TREK-1 was supported by the enrichment of TREK-1 in isolated nerve terminals determined by immunoblotting. This study represents the first evidence for a link between an anaesthetic-sensitive 2-pore domain K(+) channel and presynaptic function, and provides further support for presynaptic mechanisms in determining volatile anaesthetic action.
|Alternate Journal||Br. J. Pharmacol.|
|PubMed Central ID||PMC2078222|
|Grant List||GM 58055 / GM / NIGMS NIH HHS / United States |
R01 GM058055 / GM / NIGMS NIH HHS / United States