In Vivo Models of Smooth Muscle Growth

Abstract

Airway smooth muscle is presumed to be the major effector of the airway narrowing that occurs during bronchial provocation testing. The sensitivity of induced bronchoconstriction to lung volume in humans and animals has been interpreted as indicating that the limitation of airway narrowing in vivo is caused by an inability of airway smooth muscle to overcome the impedance imposed by the parenchymal tethering. A number of potentially interesting candidate growth-promoting substances have been identified by in vitro testing. Of particular interest are those associated with allergic inflammation since allergy is one of the best-characterised mechanisms by which asthma is induced. The increase in airway smooth muscle induced by allergen challenge is attenuated by nedocromil, an antiallergic drug which effectively reduces allergic airway responses in the rat. Hyperoxic exposure of neonatal rats causes a variety of changes in airway structure and function. The mechanism of hyperoxia-induced changes in rat airways is not known.