Activation of uterine smooth muscle contraction: Implications for eicosanoid action and interactions

U TERINE CONTRACTION and its regulation have been areas of intense interest for many years. Other presentations in this issue deal with the emerging role of prostaglandins from several sites in spontaneous and induced uterine contractility. Understanding the action of eicosanoids, their interaction with other contractile agents, and an approach to their rational use has been greatly facilitated by recent information delineating mechanisms of smooth muscle contraction and, more particularly, the mechanisms by which contractile agonists increase free intracellular calcium concentration. In this report, we will review the mechanisms of smooth muscle contraction, comparing and contrasting them with the more extensively characterized skeletal muscle. In addition, we will consider in detail recent evidence that a specific phospholipase-C, using polyphosphorylated phosphatidylinositol (PI) as substrate, is intimately involved in smooth muscle contraction and that activation of this pathway provides for potential convergence of eicosanoids and other agents affecting smooth muscle contraction.