The effect of isoflurane on the release of [H-3]-acetylcholine from rat brain cortical slices

Volatile general anaesthetics are believed to affect synaptic transmission, but their actions in the central nervous system (CNS) remains unclear. Ace tylcholine (ACh) is one of the most important neurotransmitter in the CNS a nd thus, it is possible that its release could be one of the targets for vo latile anaesthetic action. However, the effects of these agents on the rele ase of ACh are not yet fully understood. Rat brain cortical slices were loa ded with [H-3]-choline in order to study the effect of isoflurane on the re lease of [H-3]-ACh from this preparation. Isoflurane (28, 43, 54, 95 and 18 2 nM) significantly increased the basal release of [H-3]-ACh. This effect w as independent of the extracellular sodium and calcium concentration but wa s decreased by tetracaine and dantrolene, inhibitors of Ca(2+-)release from intracellular stores. These findings indicate that isoflurane may cause a Ca(2+-)release from internal stores that increases [H-3]-ACh release in rat brain cortical slices. (C) 2000 Elsevier Science Inc.