title: [Effect of ropivacaine combined with pancuronium on neuromuscular transmission and effectiveness of neostigmine and 4-aminopyridine for blockade reversal: experimental study].
abstract: OBJECTIVE
  The local anesthetic effects on neuromuscular junction and its influence on blockade produced by nondepolarizing neuromuscular blockers are still under-investigated; however, this interaction has been described in experimental studies and in humans. The aim of this study was to evaluate in vitro the interaction between ropivacaine and pancuronium, the influence on transmission and neuromuscular blockade, and the effectiveness of neostigmine and 4-aminopyridine to reverse the blockade.
  
  
  METHODS
  Rats were divided into groups (n=5) according to the study drug: ropivacaine (5μgmL(-1)); pancuronium (2μg.mL(-1)); ropivacaine+pancuronium. Neostigmine and 4-aminopyridine were used at concentrations of 2μgmL(-1) and 20μgmL(-1), respectively. The effects of ropivacaine on membrane potential and miniature end-plate potential, the amplitude of diaphragm responses before and 60minutes after the addition of ropivacaine (degree of neuromuscular blockade with pancuronium and with the association of pancuronium-ropivacaine), and the effectiveness of neostigmine and 4-aminopyridine on neuromuscular block reversal were evaluated.
  
  
  RESULTS
  Ropivacaine did not alter the amplitude of muscle response (the membrane potential), but decreased the frequency and amplitude of the miniature end-plate potential. Pancuronium blockade was potentiated by ropivacaine, and partially and fully reversed by neostigmine and 4-aminopyridine, respectively.
  
  
  CONCLUSIONS
  Ropivacaine increased the neuromuscular block produced by pancuronium. The complete antagonism with 4-aminopyridine suggests presynaptic action of ropivacaine.
authors: Departamento de Anestesiologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brasil. Electronic address: franklinbraga@terra.com.br.
authors: Angélica de Fátima
authors: Ade F
authors: Braga
authors: Farmacologia, Faculdade de Medicina, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brasil.
authors: Vanessa Henriques
authors: VH
authors: Carvalho
authors: Departamento de Anestesiologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brasil.
authors: Franklin Sarmento
authors: FS
authors: Braga
authors: Departamento de Anestesiologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brasil.
authors: Gloria Maria Braga
authors: GM
authors: Potério
authors: Departamento de Anestesiologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brasil.
authors: Filipe Nadir Caparica
authors: FN
authors: Santos
keywords: Anestésicos Locais, Ropivacaina; Animais, Ratos; Animals, rats; Bloqueadores neuromusculares; Local anesthetics, ropivacaine; Neuromuscular blockers; Nondepolarising, pancuronium; Não despolarizantes, Pancurônio