Low myometrial glycogen content compared with rectus muscle in term pregnant women before labor.

Glycogen, glucose, some nucleosides and purine base derivatives were determined in biopsies from 10 term pregnant women undergoing elective cesarean sections before labor. The concentrations were compared in the biopsies which were cut from isthmus and fundus of the uterus and m. rectus abdominis. M. rectus biopsies had 1.5 and 2 times higher concentration of glycogen than the isthmic and fundal uterine biopsies, respectively. The glucose concentration in the striated muscle was on the other hand only half that in the myometrium. The uterus displayed regional differences in concentrations of glycogen (higher in isthmus). A relatively low glycogen content in term pregnant uterine smooth muscle compared with striated muscle signifies the restricted energy demands of pregnant myometrium.