Respiratory system mechanics in mice measured by end-inflation
occlusion.
Ewart, Susan, Roy Levitt, and Wayne Mitzner.
Departments of Anesthesiology and Critical Care Medicine, and
Environmental Health Sciences, The Johns Hopkins Medical
Institutions, Baltimore, Maryland 21287
APStracts 2:0147A, 1995.
Characterization of pulmonary function parameters in mice will
facilitate the dissection of genetic mechanisms underlying airway
hyperresponsiveness. We evaluated acetylcholine (ACh)- induced
respiratory system resistance (Rrs) and elastance (Ers) in A/J and
C3H/HeJ mice and compared these results to the previously used airway
pressure time index (APTI). A low dead space ventilatory system was
designed to ventilate anesthetized mice with constant inspiratory
flow. The end-inflation occlusion method was used to measure Rrs and
Ers at baseline and following intravenous ACh (12.5 to 75.0 [mu]g/kg)
challenge. ACh induced a dose-dependent rise in Rrs and Ers in A/J
mice, while minimal changes were observed in C3H/HeJ mice. A/J mice
had a higher baseline Rrs, yet the response to ACh was independent of
baseline Rrs. Additionally, sequential ACh challenges led to
augmented responses. Rrs, Ers, and APTI were strongly correlated and
each was useful to detect differences in inter-strain cholinergic
-induced airway responsiveness. The Rrs detected the smallest
differences between the strains of mice studied.
Received 25 January 1995; accepted in final form 3 April 1995.
APS Manuscript Number A90-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.