title: Effects of halogenated anaesthetics on diaphragmatic actin-myosin cross-bridge kinetics.
abstract: BACKGROUND
  The effects of halogenated anaesthetics on cross-bridge (CB) kinetics are unclear. As halogenated anaesthetics do not markedly modify the intracellular calcium transient in the diaphragm, we used an isolated rat diaphragm preparation to assess the effects of halothane and isoflurane on CB kinetics.
  
  
  METHODS
  The effects of halothane and isoflurane (1 and 2 minimum alveolar concentration (MAC)) on rat diaphragm muscle strips were studied in vitro (Krebs-Henseleit solution, 29 degrees C, oxygen 95%/carbon dioxide 5%) in tetanus mode (50 Hz). From the force-velocity curve and using A. F. Huxley's equations, we determined the main mechanical and energetic variables and calculated CB kinetics.
  
  
  RESULTS
  At 1 and 2 MAC, isoflurane and halothane induced no significant inotropic effects. Whatever the concentrations tested, halothane and isoflurane did not significantly modify the CB number, the elementary force per CB, the attachment and detachment constants, the duration of the CB cycle and mean CB velocity.
  
  
  CONCLUSIONS
  In the rat diaphragm at therapeutic concentrations, halogenated anaesthetics do not significantly modify CB mechanical and kinetic properties.
authors.affiliation: Department of Anaesthesiology and Critical Care, Centre Hospitalier Universitaire (CHU) Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris (AP-HP), Université Pierre et Marie Curie, Paris, France. olivier.langeron@psl.ap-hop-paris.fr
authors.forename: O
authors.initials: O
authors.lastname: Langeron
authors.forename: B
authors.initials: B
authors.lastname: Bouhemad
authors.forename: G
authors.initials: G
authors.lastname: Orliaguet
authors.forename: P
authors.initials: P
authors.lastname: Coriat
authors.forename: Y
authors.initials: Y
authors.lastname: Lecarpentier
authors.forename: B
authors.initials: B
authors.lastname: Riou
mesh_terms: D000199:Actins / Q000378:metabolism*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D046508:Culture Techniques; D003964:Diaphragm / Q000187:drug effects / Q000378:metabolism; D006221:Halothane / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009218:Myosins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000199:Actins; D018685:Anesthetics, Inhalation; D007530:Isoflurane; D009218:Myosins; D006221:Halothane