Glycogen Levels in the Rat Myometrium at the End of Pregnancy and Immediately Postpartum

The glycogen content of the myometrium of the pregnant rat was found to increase dramatically just prior to parturition. At this time glycogen concentrations were similar to those in skeletal muscle and much greater than those in uteri from rats on Days 18 and 20 of pregnancy and in uteri from nonpregnant, cycling rats or ovariectomized, estrogen treated rats. Parturition, when allowed to occur naturally or when induced by oxytocin infusion, significantly reduced myometrial glycogen. These results suggest that glycogen may serve as an important source of energy in the maintenance of uterine contractions during labor. A large store of glycogen may be of particular importance when blood flow in the uterus is reduced by strong myometrial contractions.