Steroid and prostaglandin relations during the menstrual cycle.

Estrone, estradiol (E2), progesterone, prostaglandin E (PGE), and prostaglandin F (PGF) were measured simultaneously in uterine and peripheral venous plasma. PGE and PGF were determined in endometrial curettage samples. Prostaglandin levels decreased in the absence of an intact blood supply; therefore, tissue samples were all taken before hysterectomy. The levels of ovarian steroids were found to be higher in uterine venous, compared with peripheral venous plasma. PGF levels were significantly higher (P less than 0.01) in secretory endometrium compared with proliferative endometrium and throughout the cycle PGF levels in the endometrium were linearly related to the log10 concentration of E2 in uterine venous blood (P less than 0.001). PGE levels remained constant throughout the menstrual cycle.