Halothane enhances exocytosis of [3H]-acetylcholine without increasing calcium influx in rat brain cortical slices.
1. The effect of halothane on the release of [3H]-acetylcholine ([3H]-ACh) in rat brain cortical slices was investigated. 2. 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. 3. 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 Ca(2+)-release from intracellular stores or dantrolene, an inhibitor of Ca(2+)-release from ryanodine-sensitive stores 4. 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. 5. It is suggested that halothane may cause a Ca2+ release from intracellular stores that increases [3H]-ACh exocytosis in rat brain cortical slices.
Departamento de Cirurgia, Sala 4000 Faculdade de Medicina da UFMG, Belo Horizonte-Minas Gerais-Brasil. gomez@mono.icb.ufmg.br
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D000109:Acetylcholine / Q000378:metabolism*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D005089:Exocytosis / Q000187:drug effects*; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D014316:Tritium
D018685:Anesthetics, Inhalation; D014316:Tritium; D012964:Sodium; D000109:Acetylcholine; D002118:Calcium; D006221:Halothane