The effect of intra-aortic prostaglandin F-2 alpha on uterine motility in pregnant goats.

Aortic infusions of PGF-2 alpha to goats during late pregnancy had no dramatic effects on uterine motility. Only when plasma progesterone concentrations had decreased by 50% due to the luteolytic action of PGF-2 alpha did uterine activity increase. No cervical softening was detected during the infusion periods. Cervical softening was detected after the decline in progesterone concentraton and the increases in endogenous PGF and uterine motility. It is suggested that the corpus luteum, presumably by secretion of progesterone, has an inhibitory action on the cervix, preventing other hormones from inducing dilatation.