Methacholine responsiveness in mice from 2 to 8 wk of age.
Many chronic human lung diseases have their origin in early childhood, yet most murine models used to study them utilize adult mice. An important component of the asthma phenotype is exaggerated airway responses, frequently modelled by methacholine (MCh) challenge. The present study was undertaken to characterize MCh responses in mice from 2 to 8 wk of age measuring absolute lung volume and volume-corrected respiratory mechanics as outcome variables. Female BALB/c mice aged 2, 3, 4, 6, and 8 wk were studied during cumulative intravenous MCh challenge. Following each MCh dose, absolute lung volume was measured plethysmographically at functional residual volume and during a slow inflation to 20-hPa transrespiratory pressure. Respiratory system impedance was measured continuously during the inflation maneuver and partitioned into airway and constant-phase parenchymal components by model fitting. Volume-corrected (specific) estimates of respiratory mechanics were calculated. Intravenous MCh challenge induced a predominantly airway response with no evidence of airway closure in any age group. No changes in functional residual volume were seen in mice of any age during the MCh challenge. The specific airway resistance MCh dose response curves did not show significant differences between the age groups. The results from the present study do not show systematic differences in MCh responsiveness in mice from 2 to 8 wk of age.
Bozanich
Elizabeth M
EM
Division of Clinical Sciences, Telethon Institute for Child Health Research & Centre for Child Health Research, The University of Western Australia, Perth, Australia.
Jánosi
Tibor Z
TZ
Collins
Rachel A
RA
Thamrin
Cindy
C
Turner
Debra J
DJ
Hantos
Zoltán
Z
Sly
Peter D
PD
D000375:Aging / Q000473:pathology / Q000502:physiology*; D000818:Animals; D001249:Asthma / Q000473:pathology / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D007262:Infusions, Intravenous; D008168:Lung / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D008176:Lung Volume Measurements; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011247:Pregnancy; D015656:Respiratory Mechanics
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride