title: Deep inhalation prevents the respiratory elastance response to methacholine in rats.
abstract: The bronchodilator effect of deep inhalation (DI) may be assessed from the time course of respiratory system resistance (Rrs) and reactance (Xrs) measured by the forced oscillation technique at a single frequency. The aim of the study was to assess the effect of DI in the closed chest rat. Under anesthesia and mechanical ventilation, seven Brown Norway rats were given regular DI (BN-di) and six underwent continuous tidal ventilation (BN) throughout an otherwise similar methacholine (Mch) challenge protocol. Rrs and Xrs were monitored at 20 Hz and apparent respiratory system elastance (Ers) was computed from Xrs. After Mch nebulization, there was a significant increase in Rrs and Ers compared with saline. Ers, but not Rrs, decreased after the DI and BN-di were found to have lower Ers than BN. Thus, DI significantly alters Ers and its response to Mch. Computer simulations suggested reversal of increased viscoelasticity and/or inhomogeneous behavior by the DI in that model.
authors.affiliation: Laboratoire de Physiologie, Faculté de Médecine, F-54505 Vandoeuvre les Nancy, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Schweitzer
authors.forename: Bruno
authors.initials: B
authors.lastname: Demoulin
authors.forename: Gaelle
authors.initials: G
authors.lastname: Bello
authors.forename: Noelle
authors.initials: N
authors.lastname: Bertin
authors.forename: Anne Laure
authors.initials: AL
authors.lastname: Leblanc
authors.forename: François
authors.initials: F
authors.lastname: Marchal
mesh_terms: D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology; D000818:Animals; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000503:physiopathology; D016085:Bronchoconstrictor Agents; D002648:Child; D004548:Elasticity; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D016210:Methacholine Chloride; D023421:Models, Animal; D051381:Rats; D011914:Rats, Inbred BN; D012129:Respiratory Function Tests / Q000379:methods*
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride