ABSTRACT
This chapter reviews the basis for contraction of the myometrium and the role of propagation, evidence for increased electrical and metabolic coupling during parturition, and how hormones control the presence and permeability of myometrial gap junctions. It examines why gap junctions serve as sites for the coordination of action of agents that either stimulate or inhibit contractility, and theories and models of labor. The onset of contractility during labor at the end of pregnancy in all species is associated with a transformation of the myometrium from a tranquil and inert state to an aroused and vigorously active state. In the myometrium the open state would be required for the propagation of action potentials and contractions. Lack of conducted action potentials and inactivity of the myometrium are promoted by decreases in pacemaker activity, excitability of the muscle cells and cell-to-cell coupling.
