Effect of Oxygen on Multidrug Resistance in Term Human Placenta

The placenta contains efflux transporters, including P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), that limit the passage of xenobiotics and certain hormones from the maternal to the fetal circulation. The expression of these transporters changes with gestational age, yet the mechanism(s) regulating this change in expression remains unknown. However, the changes in P-gp and BCRP transporter expression coincide with changes in oxygen tension in the placenta and studies in other tissues have shown that oxygen tension regulates P-gp and BCRP expression. Here, we investigate the effects of oxygen tension on P-gp and BCRP expression in the term human placenta. We demonstrate that the expression of placental P-gp is regulated by oxygen tension, which suggests that changes in oxygenation of the placenta in the third trimester have the potential to alter fetal drug exposure.MAS