title: Effects of inhalation or incubation of oxitropium bromide on diaphragm muscle contractility in mice.
abstract: BACKGROUND
  Although oxitropium bromide is used clinically as an anticholinergic drug (i.e., parasympathetic antagonist) to relax airway smooth muscle, we examined whether it has or does not have any effects on diaphragm muscle.
  
  
  METHODS
  Three treatment sets, an oxitropium bromide inhalation only group, an oxitropium bromide inhalation plus endotoxin injection group (in vivo) and an oxitropium bromide incubation group (in vitro) were studied as to diaphragm muscle contractile properties.
  
  
  RESULTS
  Oxitropium bromide inhalation shifted force-frequency curves upward at 2 h after inhalation (p < 0.05) and inhibited the decrease of force-frequency curves due to endotoxin injection in vivo. Incubation with oxitropium bromide of untreated diaphragm muscle and diaphragm muscle injected with endotoxin did not increase the force-frequency curves dose-dependently in vitro; however, it caused both types of muscle to be fatigue resistant.
  
  
  CONCLUSIONS
  We speculate that the increment of muscle contractility with the inhalation of oxitropium bromide was induced by the antagonization of musucarinic acetylcholine receptors (mAChR). In addition, the changes of fatigue resistance provoked by oxitropium bromide, which also is speculated to antagonize mAChR, may be beneficial in the treatment of patients with COPD.
authors: Department of Clinical Physiology, Health Sciences, Tohoku University Graduate School of Medicine, Miyagi, Japan. cshindoh@med.tohoku.ac.jp
authors: Chiyohiko
authors: C
authors: Shindoh
authors: Rie
authors: R
authors: Shishido
authors: Katsuyuki
authors: K
authors: Sasaki
authors: Masahito
authors: M
authors: Miura