Maternal and fetal levels of a novel polypeptide, endothelin: evidence for release during pregnancy and delivery.
The occurrence of endothelin (ET), a recently discovered polypeptide with potent vasoconstrictor properties, was studied in maternal and umbilical blood and amniotic fluid. The level of ET-like immunoreactivity (ET-LI) in maternal plasma was in most cases below the detection limit of the radioimunoassay, i.e. less than 2 pmol/l. The median concentration of ET-LI in the umbilical artery and vein before the initiation of breathing was 14.9 and 10.9 pmol/l, respectively. When sampling was performed after fetal breathing had begun, the arterial concentration increased to 93.7 pmol/l. Labor was not associated with increased concentrations of ET-LI, however, since neonates delivered by elective cesarean section had similar ET-LI in blood and amniotic fluid as after vaginal delivery. An approximately fivefold increase in the amniotic fluid ET-LI was seen at term as compared to early mid-trimester values. Reversed phase HPLC characterization revealed that the observed ET-LI mainly corresponded to ET-1. It is suggested that ET-1 may contribute to the fetal hemodynamic changes, e.g., closure of the umbilical vessels occurring at delivery.
Nisell
H
H
Department of Obstetrics and Gynecology, Karolinska Institutet, Huddinge University Hospital, Sweden.
Hemsén
A
A
Lunell
N O
NO
Wolff
K
K
Lundberg
M J
MJ
D000653:Amniotic Fluid / Q000378:metabolism; D002585:Cesarean Section; D002851:Chromatography, High Pressure Liquid; D016232:Endothelins / Q000032:analysis / Q000378:metabolism*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism*; D011247:Pregnancy / Q000378:metabolism*; D011863:Radioimmunoassay
D016232:Endothelins