engleski

Endothelin A and B receptors change their expression levels during development of human placental villi

Endothelin receptors hale recently been found in non-vascular tissues including the human placenta. The present study investigated developmental changes in location and expression levels of endothelin A and B receptors (ETA-R, ETB-R) in human placentae and isolated trophoblast by comparing first and third trimester tissues. In the first trimester all cells and tissues were immunolabelled for ETA-R and ETB-R, whereas in third trimester placentae the syncytiotrophoblast (ETA-R, ETB-R) and macrophages (ETA-R) were unstained. Immunoblotting for both receptors revealed up to three bands at 33-35, 50 and 75 kDa, respectively, which were differentially present in the first and third trimester. Pre-adsorption of antibodies with oligopeptides used for antigen-generation weakened the immunoreactions. ETA-R protein levels decreased (P<0.05) in total villous tissue and isolated trophoblast, whereas ETB-R was unchanged. ETB-R transcripts (RT-PCR) prevailed in both stages and tissues, but in contrast to the protein levels its preponderance decreased from first trimester to term in villous tissue (P<0.01), because of a four to five-fold increase in ETA-R and only a tn a-fold (P<0.05) increase in ETB-R mRNA levels (P<0.01). We conclude that ET receptor location, intracellular processing and expression levels in human villous tissue change between the first and third trimester. This may reflect changing functions of ET-I during placental development.

Signal-transduction; Binding-sites; Cells; Heterogeneity; Subtypes; Eta; Identification; Preeclampsia; Trophoblast; Macrophages;

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