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Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model
Published on: June 18, 2013
Human placental brush-border membrane Na(+)-biotin cotransport
1Department of Pharmacology, State University of New York Health Science Center, Syracuse 13210.
The Journal of Biological Chemistry
|September 5, 1992
Summary
Researchers identified a sodium-dependent biotin cotransport system in human placental cells. This electrogenic mechanism facilitates biotin transfer across the placenta, crucial for fetal development.
Area of Science:
- Cell Biology
- Human Physiology
- Biochemistry
Background:
- Biotin (vitamin B7) is essential for fetal development.
- Transplacental transfer ensures adequate fetal biotin supply.
- The specific membrane transport mechanisms remain incompletely understood.
Purpose of the Study:
- To investigate the presence and characteristics of a sodium-biotin cotransport system.
- To determine the kinetic and substrate specificity of this transport mechanism.
- To elucidate the role of this system in transplacental biotin transfer.
Main Methods:
- Utilized purified brush-border membrane vesicles from human placental epithelial cells.
- Performed radiolabeled tracer flux measurements of biotin uptake.
- Applied kinetic analysis, substrate specificity studies, and static head determinations.
Main Results:
- Demonstrated a 25-fold increase in biotin uptake driven by a sodium gradient.
- Identified an electrogenic cotransport mechanism with a 2 Na+/biotin coupling ratio.
- Characterized biotin interaction with a single saturable site (Km = 21 microM).
Conclusions:
- Provided evidence for an electrogenic Na(+)-biotin cotransport mechanism.
- This system is located in the maternal-facing membrane of placental epithelial cells.
- This mechanism is vital for efficient transplacental biotin transport.
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