title: The influence of lidocaine and racemic bupivacaine on neuromuscular blockade produced by rocuronium. A study in rat phrenic nerve-diaphragm preparation.
abstract: OBJECTIVE
  To evaluate in vitro lidocaine and racemic bupivacaine effects in neuromuscular transmission and in neuromuscular blockade produced by rocuronium.
  
  
  METHODS
  Rats were distributed in 5 groups (n = 5) in agreement with the studied drugs: lidocaine, racemic bupivacaine, rocuronium, separately (Groups I, II, III); rocuronium in preparations exposed to local anesthetics (Groups IV, V). The concentrations used were: 20 microg/mL, 5 microg/mL and 4 microg/mL, for lidocaine, bupivacaine and rocuronium, respectively. It was evaluated: 1) amplitude of diaphragm muscle response to indirect stimulation, before and 60 minutes after separately addition of lidocaine, racemic bupivacaine and rocuronium and the association of local anesthetics - rocuronium; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP).
  
  
  RESULTS
  Lidocaine and bupivacaine separately didn't alter the amplitude of muscle response and MP. In preparations previously exposed to lidocaine and racemic bupivacaine, the rocuronium blockade was significantly larger (90.10 +/- 9.15% and 100%, respectively), in relation to the produced by rocuronium separately (73.12 +/- 9.89%). Lidocaine caused an increase in the frequency of MEPP, being followed by blockade; racemic bupivacaine produced decrease being followed by blockade.
  
  
  CONCLUSIONS
  Local anesthetics potentiated the blockade caused by rocuronium. The alterations of MEPP identify presynaptic action.
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, UNICAMP, Sao Paulo, Brazil.
authors.forename: Vanessa Henriques
authors.initials: VH
authors.lastname: Carvalho
authors.forename: Angélica de Fátima de Assunção
authors.initials: Ade F
authors.lastname: Braga
authors.forename: Franklin Sarmento da Silva
authors.initials: FS
authors.lastname: Braga
authors.forename: Yolanda Christina S
authors.initials: YC
authors.lastname: Loyola
authors.forename: Daniele Ribeiro
authors.initials: DR
authors.lastname: de Araújo
authors.forename: Mario
authors.initials: M
authors.lastname: Mantovani
mesh_terms: D000732:Androstanols / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology; D003964:Diaphragm / Q000294:innervation; D004353:Drug Evaluation, Preclinical; D004558:Electric Stimulation; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009045:Motor Endplate / Q000187:drug effects; D019148:Neuromuscular Blockade / Q000379:methods*; D009469:Neuromuscular Junction / Q000187:drug effects*; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D010791:Phrenic Nerve / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D000077123:Rocuronium; D018709:Statistics, Nonparametric
chemical_list: D000732:Androstanols; D000779:Anesthetics, Local; D003473:Neuromuscular Nondepolarizing Agents; D008012:Lidocaine; D000077123:Rocuronium; D002045:Bupivacaine