Fetal endothelin levels and placental vascular endothelin receptors in intrauterine growth retardation.
OBJECTIVE
To examine endothelin 1 (ET-1) in normal pregnancies and those complicated by severe intrauterine growth retardation (IUGR) with normal or increased fetoplacental vascular resistance as assessed by umbilical artery Doppler flow velocimetry.


METHODS
Endothelin 1 concentrations were measured by radioimmunoassay in fetal umbilical arterial and venous and maternal venous plasma, and vascular ET-1 receptors were quantified by radioligand binding methods in placental primary and secondary stem villous vessels.


RESULTS
Fetal and maternal ET-1 concentrations were similar in normal pregnancy (10-15 pmol/L) and were not influenced by mode of delivery (vaginal versus cesarean). Fetal levels were identical to control values in the growth-retarded fetuses with normal umbilical artery flow, but were markedly elevated (above 50 pmol/L) in two cases with increased fetoplacental vascular resistance. The corresponding maternal levels also appeared elevated, but to a lesser extent. Endothelin receptors were identified in placental vascular tissue. No differences in receptor-binding characteristics were observed between the groups.


CONCLUSIONS
The increased fetoplacental vascular resistance present in a proportion of pregnancies complicated by severe IUGR may be associated with elevated fetal plasma ET-1 concentrations, but with no apparent change in vascular sensitivity to the peptide.
McQeen
J
J
Medical Research Council Blood Pressure Unit, Western Infirmary, Glasgow, Scotland, United Kingdom.
Kingdom
J C
JC
Connell
J M
JM
Whittle
M J
MJ
D001667:Binding, Competitive; D016232:Endothelins / Q000097:blood* / Q000493:pharmacokinetics; D005260:Female; D005312:Fetal Blood; D005317:Fetal Growth Retardation / Q000097:blood*; D006801:Humans; D015999:Multivariate Analysis; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D017466:Receptors, Endothelin / Q000032:analysis* / Q000378:metabolism; D012044:Regression Analysis
D016232:Endothelins; D017466:Receptors, Endothelin