IMMUNOREACTIVE ADRENOMEDULLIN IN HUMAN FETOPLACENTAL TISSUES

OBJECTIVE: Adrenomedullin is increased in maternal plasma in pregnancy and has been found in very high concentrations in amniotic fluid and umbilical plasma. To identify adrenomedullin-producing tissue in pregn ancy we measured adrenomedullin concentration and distribution in feto placental tissues. STUDY DESIGN: By use of a specific radioimmunoassay we determined the concentrations of adrenomedullin and, by immunohist ochemical studies, its localization and distribution in fetal membrane s and placentas collected at elective cesarean section from 11 healthy pregnant women at term. RESULTS: The content of adrenomedullin in pla centas (117.7 +/- 7.8 pg/mg wet tissue) and fetal membranes (168.7 +/- 2.3 pg/mg wet tissue) was similar to the adrenomedullin concentration in adrenal medulla (157.3 +/- 4.4 pg/mg wet tissue). Adrenomedullin s taining appears to be greater in fetal membranes than in placentas and was localized in amnion and trophoblast cells. In term placentas posi tive staining was detected predominantly in extravillous trophoblast c ells, although a few syncytiotrophoblast cells and endothelial cells o f primary villi stained for adrenomedullin. CONCLUSION: This study pro vides evidence that is consistent with fetoplacental tissues as a site of synthesis or action of adrenomedullin during pregnancy.