The aim of this study was to simultaneously profile, using electrospraionization liquid chromatography mass spectrometry (ESI-LC-MS), prostanoids (PG) produced in the pregnant labouring (L) and non labouring (NL) myometrium.
Lower segment samples were obtained at Caesarean section from consenting pregnant women (1836 years of age) at term gestation (3841weeks). Samples were transported to the laboratory and immediately bathed in physiological Krebs solution±indometacin (1 μM) for 1 h at 4 °C (samples with indometacin referred to as treated), prior to freezing and subsequent solid phase extraction. Extracts analysed using ESI-LC-MS were quantified using calibration lines made up of commercially available standards. Results are expressed as mean pg/mg protein (as estimated by Lowry method).
About 14 and 18 PG were identified and quantified in treated (T) NL and L samples, respectively. Untreated (U) samples (both L and NL) contained 18 prostanoids. L myometrium synthesised six series-1 PG, nine series-2 PG and three series-3 PG. NL samples gave roughly the same profile, producing 6,10 and 2 series-1,2 and 3 PG correspondingly.
|6-keto-prostaglandin F1α (6-keto-PGF1α) predominates over every other PG identified in NL tissue (P<0.01)||Prostaglandin F2α (PGF2α) predominates over every other PG identified (P<0.05), including 6-keto-PGF1α in T samples of L tissue|
|No significant difference between 6-keto-PGF1α from NL and L tissue||Synthesis of 6-keto-PGF1α (U samples) is greater than any other P (P<0.05), including PGF2α (not significant)|
|PGF2α is the only PG to increase at labour versus non labour (P<0.05)|
Our data are consistent with the role of prostacyclin as a mediator of uterine quiescence at term and the role of PGF2α as an elicitor of myometrial contractions at term labour.