The regulation of phospholipase D (PLD) activity in the human amniotic
membrane was examined using primary cultures of amnion cells. Culture
d amnion cells were labelled with [H-3]oleic acid, and PLD activity wa
s determined as the amount of [H-3]phosphatidylethanol (PEt) produced
during incubation in the presence of 0.1% ethanol. PLD activity in cul
tured amnion cells was activated by addition of arginine vasopressin a
nd oxytocin. PLD activity was also stimulated by treatment with arachi
donic acid, the product of phospholipase A(2) (PLA(2)), and phospholip
ase C (PLC). These results indicate that PLD in amnion cells is activa
ted by substances present in amniotic fluid, and that cross-talk betwe
en phospholipases A(2), C and D may occur in amnion cells.