UTERINE VASCULAR CHANGES AFTER UNILATERAL INTRAUTERINE INFUSION OF INDOMETHACIN AND PROSTAGLANDIN-E(2) TO RATS SENSITIZED FOR THE DECIDUAL CELL REACTION

Uterine extracellular fluid volume (ECFV), vascular permeability (VP), and blood flow (BF) were assessed after unilateral infusion of PBS, 0.05 mM indomethacin (IM), or IM plus 1 mg/ml prostaglandin (PG) E2 (PGE2) into uteri of rats sensitized for decidualization. The study was intended to determine the importance of PGE2 in mediating uterine vascular changes during early decidualization. Uterine ECFV was assessed by the uterine volume of distribution of Cr-51-EDTA, and uterine VP by the rate of change of the uterine volume of distribution of I-125-albumin, after i.v. injection of the respective tracers. Uterine BF was determined by the radioactive microsphere technique. ECFV and VP were significantly higher in infused than in control horns after both 10 and 20 h of PBS infusion (p < 0.05). Infusion of IM abolished these vascular changes while coinfusion of PGE2 with IM returned ECFV and VP to levels not significantly different from those associated with PBS infusion. Infusion of PBS resulted in proportionate increases in both uterine weight and total uterine BF for infused horns (p < 0.05) whereas neither of these variables changed after infusion of IM. Infusion of IM+PGE2 resulted in significantly reduced tissue BF (in mul/min/mg) to infused horns because increases in uterine weights were not matched by proportionate increases in total BF. We conclude that PGs are essential for the increases in uterine VP and ECFV that precede endometrial decidualization and that PGE2 is sufficient to accomplish these vascular changes. Whereas PGs appear necessary for the increases in total uterine BF that maintain constant tissue BF during early decidualization, PGE2 alone does not appear to serve this function. In addition, the maintenance of tissue uterine BF does not seem to be essential during early decidualization since PGE2 is capable of producing normal decidualization despite reduced uterine tissue BF.