Effect of PGF-2 alpha on uterine activity, and concentrations of 13, 14-dihydro-15-keto-PGF-2 alpha in peripheral plasma during parturition in the tammar wallaby (Macropus eugenii).

Intravenous administration of PGF-2 alpha or an analogue stimulated uterine contractility in gravid uteri during seasonal quiescence and late pregnancy. The exogenous PGF-2 alpha was metabolized to 13,14-dihydro-15-keto-PGF-2 alpha (PGFM) which was assayed in peripheral plasma by a radioimmunoassay. PGFM was cleared from the circulation with a half life of 8-15 min. Blood samples were taken approximately every 6 h from Day 26 to Day 30 from tammars which were expected to give birth on Day 27-28. Basal levels of PGFM were less than 400 pg/ml, and only occasional samples contained higher PGFM concentrations. Therefore, if uterine PGF-2 alpha release is elevated at parturition in tammars, the corresponding rise of circulating PGFM is either small or of short duration.