Objective: The purpose of this study was to investigate the transport of inhibin A and to determine its effects
on fetal vascular pressure at elevated levels in the human placenta using I125
-labeled synthetic glycoprotein.Methods: Synthetic inhibinAwas prepared and was shown to be consistent with the natural form by high-pressure
liquid chromatography (HPLC) and molecular weight determination by gas-chromatography mass spectrometry.
The standardized NaI125
process yielded I125
-labeled inhibin A with a radioactivity of106
cpm/μg. This compound
was placed in the human placenta in maternal–fetal and fetal–maternal studies using antipyrine and C14
-labeled
inulin as controls to determine the bidirectional transfer of the compound.Results: Maternal–fetal and fetal–maternal clearance indices were 0.045± 0.003 and 0, respectively. In eight
placentas there was no evidence of vascular pressure changes due to the presence of up to 5000 pg of inhibin A.Conclusions: There is minimal maternal–fetal transfer and no detectable fetal–maternal transfer in normotensive
and pregnancy-induced hypertensive placentas. In addition, there are no pressure changes in the fetal vascular
system due to the clinically significant levels of inhibin A.