Alanine transport systems in isolated basal plasma membrane of human placenta
| Autor: | C. H. Smith, S. D. Hoeltzli |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
Aminoisobutyric Acids
Passive transport Physiology Placenta Biology Syncytiotrophoblast Pregnancy medicine Humans Cysteine Amino Acids Maternal-Fetal Exchange Alanine chemistry.chemical_classification Alanine transport Vesicle Cell Membrane Biological Transport Cell Biology Membrane transport Amino acid Basal plasma membrane Kinetics medicine.anatomical_structure chemistry Biochemistry Dihydroalprenolol Female |
| Zdroj: | The American journal of physiology. 256(3 Pt 1) |
| ISSN: | 0002-9513 |
| Popis: | Concentrative transfer of amino acids from mother to fetus is affected by transport across both microvillous (maternal-facing) and basal (fetal-facing) plasma membranes of the human placental syncytiotrophoblast. Isolated basal plasma membrane vesicles were used to elucidate transport systems for neutral amino acids across this membrane. The concentration dependence and inhibition of zero-trans-alanine uptake were studied and four pathways for alanine uptake were defined as follows: 1) a sodium-dependent system shared by methylaminoisobutyric acid, which has the characteristics of an A system; 2) a sodium-dependent system resistant to inhibition by methylaminoisobutyric acid, which has the characteristics of an ASC system; 3) a sodium-independent system which may resemble an L system; 4) nonsaturable uptake. The microvillous membrane of the syncytiotrophoblast possesses systems similar to 1 and 3, but system 2 is unique to the basal plasma membrane. Active and passive transport of amino acids across both microvillous and basal plasma membranes may contribute to trophoblast amino acid uptake and nutrition and to the transfer of amino acids to the fetus. |
| Databáze: | OpenAIRE |
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