Journal of Applied Physiology, Vol 59, Issue 6 1874-1878, Copyright © 1985 by American Physiological Society
Increased in vitro airway responsiveness in sheep following repeated exposure to antigen in vivo
E. M. Wagner, S. R. Kleeberger, E. W. Spannhake and G. K. Adams 3rd
We have studied the effect of repeated in vivo antigen exposure on in vitro
airway responsiveness in sensitized sheep. Fourteen sheep underwent five
biweekly exposures to aerosolized Ascaris suum antigen or saline. Following
this exposure regimen, the animals were killed and tracheal smooth muscle
and lung parenchymal strips were prepared for in vitro studies of isometric
contraction in response to histamine, methacholine, prostaglandin F2 alpha,
and a thromboxane A2 analogue. No alteration in tracheal smooth muscle
responsiveness was observed between saline- and antigen-exposed tissue. In
contrast, by use of lung parenchymal strips as an index of peripheral
airway responsiveness, significant increases in responsiveness to histamine
and a thromboxane A2 analogue (10(-6) and 10(-5) M) were observed in
antigen-exposed tissue compared with saline controls. These results
demonstrate that repeated antigen exposure in vivo selectively increase the
responsiveness of peripheral lung smooth muscle to certain chemical
mediators of anaphylaxis.
