Journal of Applied Physiology, Vol 50, Issue 5 979-983, Copyright © 1981 by American Physiological Society
Pulmonary defense mechanisms in Boa constrictor
M. M. Grant, J. D. Brain and A. Vinegar
We studied aerosol deposition and the response to inhaled particles and
irritants in lungs of Boa constrictor. Snakes which breathed submicrometric
particles radiolabeled with 99mTc retained 41.4 +/- 9.9% of the aerosol in
the trachea, 42.5 +/- 8.8% in the anterior faveolar regions, and 8.7 +/-
4.1% in the posterior saccular regions of the lungs. Low activity recovered
in the gastrointestinal tract over a 5-h period following aerosol exposure
indicated slow clearance of inhaled particles. In contrast to mammalian
lungs, there are no macrophages resident on the surface of boa lungs, and
uningested particles persist for up to 4 days without being phagocytized.
Particles and irritant stimuli (Fe2O3, endotoxin, and
N-formylmethionylphenylalanine) elicited only eosinophilic granulocytes
that were not phagocytic. The numbers of these cells peaked at 24 h
following exposure and declined gradually over the next 7 days. Lavage
fluid from stimulated snake lungs contained many large lamellar figures
continuous with tubular myelin, a form of surfactant. Very little of this
material was recovered from control lungs. Response to inhaled particles
and lung injury in boas increased surfactant release, elicited eosinophilic
granulocytes, but did not recruit phagocytic mononuclear cells.
