Inhibition by Volatile Anesthetics of Endogenous Glutamate Release from Synaptosomes by a Presynaptic Mechanism

Abstract

Inhibition of glutamate release from presynaptic nerve terminals is a potential mechanism of volatile anesthetic action. Comparison of the sensitivity of glutamate release evoked by secretogogues that act at various steps in the neurotransmitter release process suggests that halothane does not affect Ca(2+)-secretion coupling or vesicle exocytosis but inhibits glutamate release at a step proximal to Ca2+ influx, perhaps by blocking presynaptic Na+ channels. Synaptosomal glutamate release evoked by 4-aminopyridine should provide a useful system for further characterization of the presynaptic effects of anesthetics.