Halothane enhances exocytosis of 3H-acetylcholine without increasing calcium influx in rat brain cortical slices

摘要

class="enumerated" style="list-style-type:decimal">The effect of halothane on the release of [³H]-acetylcholine ([³H]-ACh) in rat brain cortical slices was investigated.Halothane (0.018 mM) did not significantly affect the basal and the electrical field stimulation induced release of [³H]-ACh. However, halothane (0.063 mM) significantly increased the basal release of [³H]-ACh and this effect was additive with the electrical field stimulation induced release of [³H]-ACh.The release of [³H]-ACh induced by 0.063 mM halothane was independent of the extracellular sodium and calcium ion concentration and was decreased by tetracaine, an inhibitor of Ca²⁺-release from intracellular stores or dantrolene, an inhibitor of Ca²⁺-release from ryanodine-sensitive stores.Using 2-(4-phenylpiperidino)-cyclohexanol (vesamicol), a drug that blocks the storage of ACh in synaptic vesicles, we investigated whether exocytosis of this neurotransmitter is involved in the effect of halothane. Vesamicol significantly decreased the release of [³H]-ACh evoked by halothane.It is suggested that halothane may cause a Ca²⁺ release from intracellular stores that increases [³H]-ACh exocytosis in rat brain cortical slices.