Myometrial prostaglandins during the human menstrual cycle

Prostaglandins E and F (PGE, PGF) and their 13,14-dihydro-15-keto metabolites were measured by radioimmunoassay in myometrium obtained from 27 women during abdominal hysterectomy for benign gynecologic conditions at defined stages of the menstrual cycle. Excepting the late secretory phase, when myometrial PGF concentrations were highest, the myometrial PGE concentration exceeded that of PGF throughout most of the menstrual cycle, especially during the late proliferative phase. The prostaglandin metabolites in myometrium did not fluctuate during the cycle, but their respective ratios with the parent prostaglandins showed changes indicative of increased biosynthesis and/or reduced catabolism of PGF and reduced biosynthesis and/or increased catabolism of PGE during the late secretory phase. The results suggest that PGE is involved in the mechanism of increased myometrial activity in the periovulatory period and that PGF may be important in the initiation of menstruation.