title: Comparisons of effects of intravenous and inhaled methacholine on airway physiology in a murine asthma model.
abstract: Airway responses to intravenous (i.v.) and inhaled (i.h.) delivery of methacholine (MCh) in BALB/c and C57BL/6 mouse strains have been compared with and without ovalbumin (OVA)-induced airway inflammation. Bronchial reactivity to MCh was assessed in anaesthetised and tracheostomised animals by using an animal ventilator (flexiVent). We partitioned the response of the lungs into airway and parenchymal components in order to compare the contributions of the airways with those of the lung parenchyma to the pulmonary mechanical responses resulting from different routes of MCh administration. Our results indicate disparate physiological responses. Intravenous MCh delivery induced a higher maximum lung resistance than i.h. MCh in OVA-treated BALB/c mice but not in C57BL/6 mice. Inhaled MCh delivery led to a significantly larger fall in lung compliance and a greater impact on peripheral airways than i.v. MCh in both strains. In conclusion, i.v. and i.h. MCh produced disparate effects in different murine strains and variant responses in inflamed airways and healthy controls. The two methods of MCh delivery have important advantages but also certain limitations with regard to measuring airway reactivity in a murine model of allergic asthma.
authors.affiliation: Department of Medical Sciences, Clinical Physiology, Uppsala University, Uppsala, Sweden. sofia.jonasson@medsci.uu.se
authors.forename: Sofia
authors.initials: S
authors.lastname: Jonasson
authors.forename: Göran
authors.initials: G
authors.lastname: Hedenstierna
authors.forename: Hans
authors.initials: H
authors.lastname: Hedenström
authors.forename: Josephine
authors.initials: J
authors.lastname: Hjoberg
mesh_terms: D000280:Administration, Inhalation; D000403:Airway Resistance / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D001249:Asthma / Q000139:chemically induced / Q000503:physiopathology*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D007275:Injections, Intravenous; D008170:Lung Compliance / Q000187:drug effects* / Q000502:physiology; D016210:Methacholine Chloride / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000494:pharmacology; D011014:Pneumonia / Q000139:chemically induced / Q000503:physiopathology; D012121:Respiration, Artificial
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D010047:Ovalbumin