Regulation of contractility in immature airway smooth muscle

Airway smooth muscle (ASM) plays an important role in the regulation of airway tone at all stages of life. While there has been much examination of the mechanisms by which adult ASM contracts and relaxes, especially given its importance in diseases such as asthma, there has been substantially less exploration of immature ASM. Here, given the fact that embryonic/fetal and postnatal lung development is associated with substantial and rapid changes in airway structure and size, the immature ASM must maintain the capability to contract/relax as well as proliferate. Beyond this obvious physiological relevance, the clinical importance of understanding the developing ASM lies in its potential role in diseases of the newborn that predispose infants to adult problems such as asthma. In this chapter we briefly describe the current state of knowledge regarding immature ASM and mechanisms that regulate its contractility.