PREECLAMPSIA AND GESTATIONAL-AGE DIFFERENTLY ALTER BINDING OF ENDOTHELIN-1 TO PLACENTAL AND TROPHOBLAST MEMBRANE PREPARATIONS

The aim of the study was to compare the binding of endothelin-1 (ET-1) to membranes from placental tissue and trophoblast cells in normal an d pre-eclamptic pregnancies. Plasma membranes from placental tissue an d trophoblastic cells were prepared from 15 control and 18 pre-eclampt ic pregnancies at either preterm (weeks 31-36) or term (weeks 37-40). ET-1 binding to tissue membranes was measured by a radioreceptor assay . In addition, binding of 56 nmol/l [I-125]ET-1 to plasma membranes of trophoblastic cells was determined. In pre-eclampsia, placental membr anes bound less (P < 0.01) ET-1 owing to fewer (P < 0.01) receptors at preterm than in the corresponding preterm controls. In contrast, bind ing of [I-125]ET-1 to plasma membranes of trophoblast cells was higher (P < 0.01) in pre-eclampsia at both gestational stages than in the co ntrols. Incubation of trophoblast cells with hydralazine reduced bindi ng by 70%. We conclude that pre-eclampsia is associated with changes i n the binding of ET-1 to its placental receptors. Moreover, the data s uggest that pre-eclampsia affects non-trophoblast cells in the opposit e manner to the trophoblast.