Activation of Phospholipase D in Cultured Human Amnion Cells Kumiko lnamoriA, Norimasa sagawac, Masaki ~ase~awa~, Hiroaki ltohA, Juri yanoB and Takahide ~ori~

The regulation of phospholipase D (PLD) activity in the human amniotic membrane was examined using primary cultures of amnion cells. Cultured amnion cells were labelled with (3~)oleic acid, and PLD activity was determined as the amount of (3~)phosphatidylethanol (PEt) produced during incubation in the presence of 0.1% ethanol. PLD activity in cultured amnion cells was activated by addition of arginine vasopressin and oxytocin. PLD activity was also stimulated by treatment with arachidonic acid, the product of phospholipase A? (PLA2), and phospholipase C (PLC). These results indicate that PLD in amnion cells is activated by substances present in amniotic fluid, and that cross-talk between phospholipases A2, C and D may occur in amnion cells.