title: General anaesthetic modification of synaptic facilitation and long-term potentiation in hippocampus.
abstract: The synaptic integrative properties of facilitation and potentiation are important determinants of cortical neurone excitability. The present study measured the effects of halothane and methoxyflurane on synaptic facilitation, paired-pulse potentiation, and long-term potentiation (LTP) in CA1 pyramidal neurones of rat hippocampal slices. Methoxyflurane 0.16vol% and halothane 1.2 vol% depressed population spike amplitudes by approximately 100%, but halothane did so with relatively little (less than 10%) depressant effect on the field excitatory postsynaptic potential (EPSP). Both agents enhanced EPSP facilitation, halothane more than methoxyflurane. Halothane consistently enhanced paired-pulse population spike potentiation; methoxyflurane sometimes diminished it. Halothane reduced the probability of LTP induction to an extent correlated with block of population spike responses in the inducing stimulus train (r = 0.92); methoxyflurane did not block LTP. The results suggest that these agents affect cortical excitability by multiple actions, the distribution of actions being specific to each agent.
authors.affiliation: Department of Anesthesia, Stanford University School of Medicine, CA94305-5117.
authors.forename: M B
authors.initials: MB
authors.lastname: MacIver
authors.forename: D L
authors.initials: DL
authors.lastname: Tauck
authors.forename: J J
authors.initials: JJ
authors.lastname: Kendig
mesh_terms: D000818:Animals; D004357:Drug Synergism; D004594:Electrophysiology; D005071:Evoked Potentials; D006221:Halothane / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008733:Methoxyflurane / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D017981:Receptors, Neurotransmitter; D008733:Methoxyflurane; D006221:Halothane