In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 310, No. 9 ( 2016-05-01), p. R828-R836
Abstract:
Membrane transporters are considered essential for placental amino acid transfer, but the contribution of other factors, such as blood flow and metabolism, is poorly defined. In this study we combine experimental and modeling approaches to understand the determinants of [ 14 C]phenylalanine transfer across the isolated perfused human placenta. Transfer of [ 14 C]phenylalanine across the isolated perfused human placenta was determined at different maternal and fetal flow rates. Maternal flow rate was set at 10, 14, and 18 ml/min for 1 h each. At each maternal flow rate, fetal flow rates were set at 3, 6, and 9 ml/min for 20 min each. Appearance of [ 14 C]phenylalanine was measured in the maternal and fetal venous exudates. Computational modeling of phenylalanine transfer was undertaken to allow comparison of the experimental data wit h predicted phenylalanine uptake and transfer under different initial assumptions. Placental uptake (mol/min) of [ 14 C]phenylalanine increased with maternal, but not fetal, flow. Delivery (mol/min) of [ 14 C]phenylalanine to the fetal circulation was not associated with fetal or maternal flow. The absence of a relationship between placental phenylalanine uptake and net flux of phenylalanine to the fetal circulation suggests that factors other than flow or transporter-mediated uptake are important determinants of phenylalanine transfer. These observations could be explained by tight regulation of free amino acid levels within the placenta or properties of the facilitated transporters mediating phenylalanine transport. We suggest that amino acid metabolism, primarily incorporation into protein, is controlling free amino acid levels and, thus, placental transfer.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.00405.2015
Language:
English
Publisher:
American Physiological Society
Publication Date:
2016
detail.hit.zdb_id:
1477297-8
SSG:
12
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