title: Influence of stimulus frequency on blockade induced by pancuronium and rocuronium: study on rats phrenic nerve-diaphragm preparation.
abstract: OBJECTIVE
  To evaluate the influence of two stimulation frequencies on the installation of neuromuscular blockade produced by pancuronium and rocuronium on the rat diaphragm.
  
  
  METHODS
  Diaphragms were submitted to an indirect frequency stimulation of 0.1 and 1 Hz (Groups I and II, respectively). Subgroups were formed (n=5) according to the neuromuscular blocker employed (pancuronium-2 microg/ml and rocuronium-4 microg/ml). The twitch height depression was evaluated at 5, 15 and 30 minutes after adding the neuromuscular blocker.
  
  
  RESULTS
  The decrease in twitch height was greater (p<0.01) with a frequency of 1 Hz at all time periods studied both in preparations that are blocked with pancuronium and in those that are blocked with rocuronium.
  
  
  CONCLUSIONS
  The frequency of stimulation interferes significantly with the installation of neuromuscular blockade produced by pancuronium and rocuronium, since the reduction in amplitude of the rat diaphragm response was greater for 1 Hz frequencies, at all periods studied.
authors.affiliation: Department of Anesthesiology, Faculty of Medical Sciences, UNICAMP, São Paulo, Brazil. franklinbraga@terra.com.br
authors.forename: Angélica de Fátima de Assunção
authors.initials: Ade F
authors.lastname: Braga
authors.forename: Derli Conceição
authors.initials: DC
authors.lastname: Munoz
authors.forename: Franklin Sarmento da Silva
authors.initials: FS
authors.lastname: Braga
authors.forename: Daniele Ribeiro de
authors.initials: DR
authors.lastname: Araujo
authors.forename: Glória Maria Braga
authors.initials: GM
authors.lastname: Potério
authors.forename: Mario
authors.initials: M
authors.lastname: Mantovani
mesh_terms: D000732:Androstanols; D000818:Animals; D003964:Diaphragm / Q000187:drug effects / Q000294:innervation; D004558:Electric Stimulation / Q000379:methods*; D008297:Male; D019148:Neuromuscular Blockade / Q000379:methods; D003473:Neuromuscular Nondepolarizing Agents; D010197:Pancuronium; D010791:Phrenic Nerve / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D000077123:Rocuronium
chemical_list: D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D010197:Pancuronium; D000077123:Rocuronium