Aerosolized methacholine-induced bronchoconstriction and pulmonary hyperinflation in rats.
The body plethysmography (BPG) is a useful tool for analyzing pulmonary function in small animals because it simultaneously measures airway resistance (R (aw)) and functional residual capacity (FRC). We previously described a BPG with the enclosed environment maintained at body temperature and water vapor-saturated. We found dose-dependent increases in R (aw) in response to inhaled methacholine (Mch) with no apparent increase in FRC in intratracheally intubated rats without paralysis. To resolve this apparent inconsistency in clinical observations, we repeated the study using a newly developed BPG that allowed us to shorten the interval between Mch-inhalation and measurements by about two-thirds. Using Mch concentrations of 0, 0.5, 1.0, 2.0 and 4.0 mg/ml each for 2 min, both parameters increased in a dose-dependent fashion with FRC (mean +/- SE) values of 3.77 +/- 0.16, 4.43 +/- 0.26, 4.75 +/- 0.34, 5.02 +/- 0.49 and 5.34 +/- 0.38 ml and R (aw) values of 18.6 +/- 3.9, 21.6 +/- 4.9, 35.0 +/- 6.9, 49.0 +/- 8.8 and 65.7 +/- 8.8 ml/s/Pa, respectively. Immediate measurement after Mch-inhalation demonstrated profound bronchoconstriction associated with dose-dependent increases in FRC.
Kondo
Tetsuri
T
Department of Respiratory Medicine, Tokai University Hachioji Hospital, 1838 Ishikawa, Hachioji, Tokyo, 192-0032, Japan. tetsuri@hachioji-hosp.tokai.ac.jp
Tanigaki
Toshimori
T
Tsuji
Chizuko
C
Ishii
Hiroshi
H
Tazaki
Gen
G
Kondo
Yuusuke
Y
D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D001249:Asthma / Q000503:physiopathology; D016084:Bronchoconstriction / Q000187:drug effects* / Q000502:physiology; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005652:Functional Residual Capacity; D008168:Lung / Q000473:pathology / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D010993:Plethysmography, Whole Body; D051381:Rats; D017208:Rats, Wistar
D000336:Aerosols; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride