PHOSPHOINOSITIDE METABOLISM IN AIRWAY SMOOTH-MUSCLE

Agonist-stimulated hydrolysis of phosphatidylinositol 4,5-bisphosphate , which generates inositol 1,4,5-trisphosphate and sn-1,2-diacylglycer ol, is thought to be one of the major mechanisms underlying pharmacome chanical coupling in airway smooth muscle. This article is a review of the currently available information on phosphoinositide and inositol 1,4,5-trisphosphate metabolism in this tissue and includes data on ino sitol 1,4,5-trisphosphate-induced Ca2+ release and the receptor mediat ing this effect. The final section outlines the potential mechanisms u nderlying physiological regulation of phosphoinositide metabolism by o ther second-messenger pathways operative in this tissue.