Indomethacin inhibits the uptake of sodium by ovine trophoblastic tissue in vitro

Blastocysts from several species synthesize prostaglandins in vitro, but the exact functions of the prostaglandins are unknown. The purpose of this study was to determine if indomethacin, an inhibitor of prostaglandin synthesis, would inhibit the uptake of ²²sodium (²²Na]) by ovine trophoblastic tissue. To determine the concentration of indomethacin that would inhibit the synthesis of PGF_2α and 13,14-dihydro-15-keto-PGF_2α (PGFM) by blastocysts, blastocysts were collected from ewes 16 days after mating, sliced into pieces approximately 2 mm in length and incubated for 48 h at 37°C in 2 ml of medium containing either 0, 0.2, 0.4, 0.8 or 1.6 mM of indomethacin. Concentrations of indomethacin mM reduced (P<.01) trophoblastic release (ng/μg DNA) of PGF_2α from

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, reduced PGFM from

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, and inhibited formation of trophoblastic vesicles. In a second experiment, blastocysts were recovered from ewes 16 days after mating and pieces of trophoblast were incubated with ²²Na] and either 0 or 0.4 mM of indomethacin. Indomethacin reduced the uptake of ²²Na], which is an indirect measure of the transport of water across epithelia, from 3680 ± 1118 to 934 ± 248 cpm/μg DNA (P<.03) and prevented formation of trophoblastic vesicles. Prostaglandins produced by ovine blastocysts might be involved in controlling uptake of water, which is essential for expansion of blastocysts.