The transfer of prostaglandin E2 across ovine fetal membranes in vivo.
OBJECTIVE
This study investigated whether prostaglandin E2 (PGE2) can cross intact fetal membranes in vivo.


METHODS
We have developed a novel ovine model using in vivo dialysis systems, positioned between the fetal membranes and decidua and in the amniotic cavity. Sheep were given 25 microCi, 50 ng [3H]PGE2 or 1 mg PGE2 to the amniotic cavity, and radioactivity or PGE2/PGEM concentrations in dialysates were determined.


RESULTS
Endogenous basal PGE2 concentrations were significantly higher in extra-amniotic than in intra-amniotic dialysates (715 +/- 436 versus 80 +/- 31 pg/mL; mean +/- standard error of the mean; P < .05). After injection of [3H]PGE2 into the amniotic cavity, no radioactivity was detected in the extraamniotic dialysate, and this was not influenced by labor induced by ACTH administration to the fetus. In contrast, intra-amniotic injection of 1 mg PGE2 resulted in marked transfer of PGE2 across the fetal membranes to the extra-amniotic dialysis system.


CONCLUSIONS
These results suggest that PGE2 can cross the ovine fetal membranes in vivo, escaping metabolism in the chorion.
Johnston
P C
PC
Department of Obstetrics and Gynecology, University of Glasgow, Royal Infirmary, Scotland.
Greer
I A
IA
Brooks
A N
AN
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D015237:Dinoprost / Q000031:analogs & derivatives / Q000032:analysis / Q000276:immunology; D015232:Dinoprostone / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000032:analysis / Q000276:immunology / Q000378:metabolism / Q000493:pharmacokinetics*; D005321:Extraembryonic Membranes / Q000378:metabolism*; D005260:Female; D007267:Injections; D017551:Microdialysis / Q000379:methods; D010120:Oxytocics / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D011863:Radioimmunoassay; D012756:Sheep; D013997:Time Factors; D014316:Tritium
D010120:Oxytocics; D014316:Tritium; C008228:15-keto-13,14-dihydroprostaglandin F2alpha; C025087:15-keto-13,14-dihydroprostaglandin E2; D000324:Adrenocorticotropic Hormone; D015237:Dinoprost; D015232:Dinoprostone