Journal of Applied Physiology, Vol 64, Issue 3 1009-1016, Copyright © 1988 by American Physiological Society
Immunoglobulin E anaphylaxis in rabbits: mechanisms of pulmonary resistance and compliance changes
M. P. Habib, A. M. Dunn, R. E. Sobonya, C. C. Baumgartener, J. D. Newell and M. Halonen
Department of Internal Medicine, College of Medicine, University of Arizona, Tucson.
Factors causing changes in pulmonary resistance and dynamic compliance with
immunoglobulin (Ig) E anaphylaxis in spontaneously breathing rabbits were
assessed in ventilated rabbits using tantalum bronchography and wet-to-dry
wt ratios. Ventilated rabbits demonstrated changes in resistance and
compliance similar to spontaneously breathing rabbits. Chlorpheniramine
pretreatment prevented increases in resistance but not decreases in
compliance. Anaphylaxis constricted small (less than 1 mm) airways 20.9 +/-
16.0% (mean +/- SD) and intermediate (between 1 and 3 mm) airways 21.8 +/-
19.8%. Chlorpheniramine (10 mg/kg) prevented small airway changes and
attenuated those in intermediate airways. Chlorpheniramine prevented
histamine-induced constriction of small (23.6 +/- 15.7%) and intermediate
(17.6 +/- 15.0%) airways. Lung wet-to-dry wt ratios were unchanged. Changes
in resistance and compliance during rabbit IgE anaphylaxis are not due to
changes in tidal volume or frequency. Histamine, via H1 receptors, is the
principal mediator of pulmonary resistance increases but not dynamic
compliance reductions. Chlorpheniramine-sensitive increases in resistance
are caused by constrictions of intermediate and small airways, whereas the
chlorpheniramine-resistant decrease in compliance is not caused directly by
constriction of the smallest measurable airways (0.25 mm) or changes in
lung water.
