title: Comparative presynaptic effects of the volatile anesthetics sevoflurane and isoflurane at the mouse neuromuscular junction.
abstract: BACKGROUND
  Sevoflurane and isoflurane are anesthetics that cause muscle relaxation and potentiate the effects of neuromuscular blocking agents. Their presynaptic mechanisms of action are not understood completely, especially at the motor nerve terminal.
  
  
  METHODS
  We compared the presynaptic effects of these anesthetics on the exocytosis of synaptic vesicles labeled with the dye FM1-43 at the mouse neuromuscular junction.
  
  
  RESULTS
  Neither anesthetic evoked spontaneous exocytosis of synaptic vesicles, but both significantly inhibited the depolarization evoked by 4-aminopyridine and veratridine, suggesting a putative action on sodium channels. Exocytosis evoked by veratridine was inhibited by tetrodotoxin alone or in conjunction with sevoflurane or isoflurane, indicating that both agents may target voltage-gated sodium channels.
  
  
  CONCLUSIONS
  We suggest that sevoflurane and isoflurane inhibit exocytosis evoked by sodium-dependent depolarization and might act on tetrodotoxin-sensitive sodium channels. These findings contribute to a better understanding of some clinical neuromuscular effects induced by these anesthetics.
authors: Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil.
authors: Matheus De
authors: MD
authors: Castro Fonseca
authors: Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil.
authors: Janice Henriques
authors: JH
authors: Da Silva
authors: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, MG, Brasil.
authors: Vany Perpetua
authors: VP
authors: Ferraz
authors: Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
authors: Renato Santiago
authors: RS
authors: Gomez
authors: Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil.
authors: Cristina
authors: C
authors: Guatimosim
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D003964:Diaphragm / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D005260:Female; D007530:Isoflurane / Q000494:pharmacology*; D008738:Methyl Ethers / Q000494:pharmacology*; D051379:Mice; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D017729:Presynaptic Terminals / Q000187:drug effects* / Q000502:physiology; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane
keywords: FM1-43; exocytosis; isoflurane; neuromuscular junction; sevoflurane; synaptic vesicle