TISSUE PHOSPHOLIPIDS DURING HUMAN-PREGNANCY BY P-31 NMR - MYOMETRIUM,DECIDUA, PLACENTA AND FETAL MEMBRANES

The biophysical environment formed by phospholipids, rather than the a mount of functional proteins, can be rate limiting for factors control ling myometrial contractility and pregnancy maintenance, We therefore studied myometrial, decidual, placental and fetal membrane phospholipi ds using the P-31 NMR spectrum, This enabled us to identify bulk phosp holipids over 0.05 mmol/kg, The method was checked for reliability for the reproductive tissues studied, The chemical shift of phospholipid standards was slightly different according to whether a single compoun d or a mixture was analyzed, The bulk phospholipids found were phospha tidylcholine (PC), phosphatidylethanolamine, sphingomyelin (SM) and ph osphatidylinositol. The ratio PC/SM decreased during pregnancy in the decidua, placenta and fetal membranes, but not in the myometrium. Preg nancy did not induce significant changes in the total myometrial phosp holipids. Their composition was stable even during clinical labor, The fetal tissues, placenta and fetal membranes contained about twice as much phospholipid as the maternal tissues, myometrium and decidua, The re was no sign of lysocompounds, cardiolipin or phosphatidic acid, Thi s supports the view that the extraction and analyzing techniques used earlier probably created artefacts, The increased fluidity of the myom etrial and placental phospholipids during pregnancy may depend on fact ors other than the composition of phospholipids.