Perinatal Metabolism of Hemopexin and Heme 1

Abstract

Summary

Sera from fetal, newborn, and juvenile rabbits were found to have lower Hx levels than those of their mothers but approached the normal adult range by 30 to 60 days of age. Inadequate materno-fetal transport of Hx contributed to low fetal and neonatal serum levels, since only small amounts of homologous ¹²⁵I-Hx passed from the maternal circulation to fetal serum and tissues. However, substantial amounts were found in fetal and maternal placentae. Heterologous HHx did not pass. Small amounts of ¹⁴C- and ⁵⁹Fe-heme also crossed the materno-fetal barrier of rabbits, probably directly across the placenta. Furthermore, our findings suggested bidirectional transplacental passage of heme.