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L-proline transport by brush border membrane vesicles prepared from human placenta
The Journal of Physiology
|June 1, 1981
Summary
Human placental transport of L-proline is sodium-dependent and electrogenic. This amino acid uptake mechanism is crucial for transplacental transfer, utilizing a specific carrier system.
Area of Science:
- Biochemistry
- Cell Biology
- Physiology
Background:
- The placenta facilitates nutrient transfer from mother to fetus.
- Understanding amino acid transport mechanisms is vital for fetal development.
Purpose of the Study:
- To investigate the mechanism of L-proline transport across the human placental brush border membrane.
- To elucidate the role of sodium and electrical potential in this process.
Main Methods:
- Isolation of brush border microvillous plasma membranes from human term placenta.
- Preparation of right-side-out vesicles for transport assays.
- Measurement of L-proline uptake under various ionic and potential gradients.
Main Results:
- L-proline transport is time-dependent and exhibits transient accumulation driven by sodium gradients.
- Transport is sodium-dependent and electrogenic, influenced by potassium diffusion potential.
- Saturation kinetics observed, with a Km of approximately 1 mM and Vmax of 2 nmol/mg protein/min.
- Transport is competitively inhibited by other amino acids and glycyl-L-proline.
Conclusions:
- L-proline transport across the human placental syncytiotrophoblast brush border is a sodium-dependent, electrogenic process.
- Findings provide insights into the molecular mechanisms of transplacental amino acid transfer.