Immunoreactive dynorphine in maternal blood, umbilical vein and amniotic fluid.

Immunoreactive dynorphin (ir-Dyn) was measured in maternal blood, umbilical vein and amniotic fluid after its extraction by passage through Sep Pak (C18 Waters). No significant change was observed in the plasma level of ir-Dyn in the first and second trimester of pregnancy as compared with plasma obtained from non-pregnant women. However, a 2.2 fold increase in ir-Dyn levels was observed during the third trimester as well as at delivery (1.07 and 1.09 pmoles per ml, respectively as compared with 0.48 pmoles per ml in control plasma). High levels of ir-Dyn were also found in the amniotic fluid (0.83 pmoles per ml) and the umbilical vein plasma (2.2 pmoles per ml). High pressure liquid chromatography analysis of maternal plasma ir-Dyn obtained at the end of the third trimester of pregnancy revealed the presence of multiple forms of ir-Dyn, the major peaks corresponding to the elution time of some previously identified placental ir-compounds namely Dyn-(1-11) and Dyn-(1-13). These data indicate that the levels of ir-Dyn in the maternal plasma at the third trimester of pregnancy and at delivery increase, a placental contribution to this phenomenon could be speculated.