Transport of amino acids by placenta

Transfer Across Perfused Human Placenta. II. Free Fatty Acids

“…For comparison, a similar but not strictly comparable record has been compiled from data collected in this laboratory for transfer across guinea pig placenta. The studies on placental transfer in the guinea pig were undertaken with an in situ perfusion technique [2,3,10,13,14], and measurements were made in the reverse direction, from fetal to maternal circulation. Antipyrine was not used regularly as a base line, so that many of the figures repre-> sent rough estimates done at different times in differ- 'Transfer rates are presented as a percentage of antipyrine clearance.…”

“…In a previous study of amino acid transport [3], the measurement of uptake of a-aminoisobutyric acid by placental slices proved to be a useful technique. Although there were many similarities between guinea pig and human placenta, only the latter could be demonstrated to be responsive to insulin.…”

“…In perfusion experiments with antipyrine-iVmethyl- 3 H, palmitic acid-l- 14 C, and L-leucine-4,5-3 H, the first two compounds were extracted from the perfusate with chloroform. Two milliliters of perfusate were extracted four times with 2 ml chloroform.…”

Placental Amino Acid Uptake. II. Tissue Preincubation, Fluid Distribution, and Mechanisms of Regulation

“…Amino acids are actively transported by the placenta and their concentrations are higher in fetal blood than in maternal (4, 5 , 7, 11, 24). The relatively large quantities of amino acids required for the needs of the fetus and their importance in fetal nutrition lead t o the use of i n vitro techniques for the study of placental transport mechanisms (6,16,17,23). …”

In Vitro Models Using the Human Placenta to Study Fetal Exposure to Drugs

“…The fi rst is when the tissue obtained from uncomplicated pregnancies and can be used to study the effects of experimental condition on tissue survival and function. For instance, placental explants have been used to investigate uptake and effl ux of amino acids, vitamins and sugars (Dancis et al 1968;Miller and Berndt, 1974;Ng et al 1981), and to identify receptors, binding sits, and factors regulating transport processes. In addition, placenta explants have been used to study how does the mode of labor (cesarean section vs. vaginal delivery) affect the sensitivity of placental tissue to cytokines as tumor necrosis factor α (TNF α ), prostaglandin (PGE2), prostacyclin and non steroidal antiinfl ammatory drugs (Turner et al 2002;Turner et al 2004).…”