[H-3] PROSTAGLANDIN UPTAKE INVIVO BY RABBIT UTERINE TISSUES AND BLASTOCYSTS

Day-6 pregnant rabbits were anesthetized and subjected to a mid-ventral laparotomy. [3H] Prostaglandin F2α) (PGF2α) [3H]PGE2, [14C]Urea or [14C]Sucrose were instilled into the uterine lumen via the uterotubal junction. The amounts instilled/uterine horn were respectively 3.7 ± 0.3, 3.5 ± 0.3, 5.7 ± 1.3 and 2.7 ± 1.6 μCi in 20μl of buffer. Animals were killed at 1, 2, 9, 19 or 21 h after radioactive instillation, and the amounts of radioactivity in blastocysts, uterine tissue, peritoneal cavity washings and urine evaluated by liquid scintillation spectrometry. A gradient of radioactivity was observed from the uterotubal junction to the cervical end of the uterus. Large amounts of [3H]PG were found in the injected horn and associated blastocysts with a considerable crossover to the non-injected horn, but little in the associated blastocysts. Much of the blastocyst associated-[3H]PG remained unmetabolized. Large amounts of metabolized [3H] were found in urine. [14C]Urea was taken up by uterine tisse in the injected horn, but there was little crossover to the non-injected horn. Urea was also found in urine. Much of the [14C]Sucrose remained in the injected horn, and little was recovered from the urine. It was found that at 9 h, but not at 19 h, after [3H]PG instillation, the PG was localized at the site of the blastocysts in the injected but not in the contralateral horn. Significantly more [3H]PGF2α than [3H]PGE2 was localized in this situation. [14C]Urea was not localized at the site of the blastocysts in urea injected horns. Injection of the same amount of [3H]PGE2 into the uterine lumen did not compromise subsequent implantation and short-term embryonic growth. These results indicate that PGs are handled differently by blastocysts and uterine tissue than urea, and imply some specificity related to the process of implantation. © 1990.