Journal of Applied Physiology, Vol 66, Issue 3 1120-1126, Copyright © 1989 by American Physiological Society
Corticosteroids decrease airway hyperresponsiveness in the Basenji-Greyhound dog model of asthma
M. J. Darowski, V. M. Hannon and C. A. Hirshman
Department of Anesthesiology, Johns Hopkins University, Baltimore, Maryland 21205.
Methacholine and citric acid responses were assessed before, during, and
after 6 wk of oral treatment with either placebo or methylprednisolone (2
mg.kg-1.day-1) in 12 Basenji-Greyhound dogs. Bronchoalveolar lavage was
performed in three dogs in each group before, during, and after
pretreatment. Base-line airway resistance and dynamic compliance did not
change with treatment in any of the groups. Placebo treatment had no
demonstrable effect on methacholine and citric acid responsiveness.
Methylprednisolone treatment abolished the constrictor response to citric
acid during the 4th and 6th wk of treatment and significantly reduced
methacholine responsiveness during the 3rd and 5th wk of treatment.
Methylprednisolone treatment was associated with a marked reduction in the
percent of eosinophils, but not mast cells, in the bronchoalveolar lavage
fluid during the 7th wk. Blood eosinophil counts were also markedly reduced
in the methylprednisolone-treated group compared with the placebo-treated
group during the 7th wk. The decrease in numbers of eosinophils in blood
and bronchoalveolar lavage fluid suggests interference with the
inflammatory process as a possible mechanism for the observed reduction in
airway hyperresponsiveness in the Basenji-Greyhound dog.
