The bidirectional transfer and fetal vascular pressure changes due to the presence of 125I-labeled inhibin A in the ex-vivo human placental model.

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 125I-labeled synthetic glycoprotein.

Methods: Synthetic inhibin A was 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 Na125I process yielded 125I-labeled inhibin A with a radioactivity of 10(6) cpm/microg. This compound was placed in the human placenta in maternal-fetal and fetal-maternal studies using antipyrine and 14C-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.