The Bidirectional Transfer and Fetal Vascular Pressure Changes Due to the Presence of [Formula: see text] I-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 (125)I -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 Na(125)I process yielded (125)I -labeled inhibin A with a radioactivity of 10(6) cpm/μg. This compound was placed in the human placenta in maternal–fetal and fetal–maternal studies using antipyrine and (14)C -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.