Placental transfer and fetal uptake of amino acids in the pregnant ewe

Young, Maureen; Fadyen, I. R. Mc.

doi:10.1515/jpme.1973.1.3.174

Cited by 41 publications

(14 citation statements)

References 26 publications

(28 reference statements)

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“…It is apparent that some amino acids, notably serine, have a higher concentration in fetal blood; whereas others, such as the basic amino acids lysine, arginine, and histidine, are approximately at the same concentration in the two blood streams. The total molar concentration of the amino acids measured in this study was 1.7 times greater in fetal blood (4.79 vs. 2.81 mM), in agreement with earlier observations about the a-amino 1430 Lemons, Adcock, Jones, Naughton, Meschia, and Battaglia nitrogen content of maternal and fetal blood (4) or plasma (1,20). Umbilical venous-arterial differences for amino acids.…”

Section: Resultssupporting

confidence: 91%

“…The observation that several amino acids, both essential and nonessential, can cross the placenta rapidly and against a concentration gradient (1-6) has led to the suggestion that the placenta may transport to the fetus all of the amino acids which are needed for protein synthesis (1). A related assumption Received for publication 10 May 1976 and in revised form 27 August 1976. is that in the fetus there is virtually no formation and degradation of amino acids (7).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Umbilical uptake of amino acids in the unstressed fetal lamb.

Ja¹,

Ew²,

Jones³

et al. 1976

J. Clin. Invest.

267

120

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A B S T R A C T The whole blood concentrations of 22 amino acids were measured in a chronic, unstressed fetal lamb preparation. Samples were taken daily from the umbilical artery, umbilical vein, and maternal artery over the latter quaiter of gestation. 73 sets of samples (from the umbilical artery and vein and the maternal artery) from 13 animals were analyzed for amino acid levels. Oxygen contents were determined simultaneously in 48 sets (umbilical artery and vein) to relate fetal oxygen consumption to amino acid uptake via the umbilical circulation.The results indicate that there is no umbilical uptake of the acidic amino acids, glutamate and aspartate; there is, in fact, a net flux of glutamate out of the fetus into the placenta. As both of these amino acids are major constituents of body proteins, the data indicate that they are formed within the fetus. The umbilical uptake of some neutral and basic amino acids (e.g., valine, leucine, isoleucine, arginine, phenylalanine, and tyrosine) is in considerable excess of estimated growth requirements, suggesting that some amino acids undergo extensive transamination and oxidative degradation in the fetus.Finally, the net uptake of nitrogen, carbon, and calories by the growing ovine fetus in the formn of amino acids, glucose, and lactate is compared to estimated requirements as determined in previous studies.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Umbilical uptake of amino acids in the unstressed fetal lamb.

Ja¹,

Ew²,

Jones³

et al. 1976

J. Clin. Invest.

267

120

View full text Add to dashboard Cite

show abstract

“…The tip of the catheter in the fetal jugular vein was near the entrance to the right auricle and since there was no free flow of blood from the head, the sample would be repres^Atative of blood returning from the liver which might account for the low concentfations of alanine and glycine observed in the control samples in comparison with those reported previously for umbilical vein and artery (YouNG and McFADYEN [29]). However, the composition of the umbilical vein blood taken from the undisturbed twins, remaining 14 days 'in utero' after surgery to the sibling, though similar to the earlier reported values also have low alanine levels which suggests that the low jugular vein alanine might also be the result of fetal surgery.…”

Section: Discussionmentioning

confidence: 70%

The influence of intra-uterine surgery and of fetal intravenous nutritional supplements ‘in utero’ on plasma free amino acid homeostasis in the pregnant ewe

Young¹,

Soltész²,

Noakes³

et al. 1975

Journal of Perinatal Medicine

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“…Amino acids have an important role in fetal metabolism and growth, and in a number of species (sheep, guinea-pig, human) the concentrations of a wide range of individual amino acids are maintained at higher levels in the fetal than maternal circulation by active transfer mechanisms (Young & McFadyen, 1973;Lemons, 1979;Faichney, 198 1). This fetal-maternal gradient is present irrespective of maternal concentrations and can be demonstrated in the perfused placenta (Young, 1979).…”

Section: Introductionmentioning

confidence: 99%

Blood amino acids in the pregnant mare and fetus: the effects of maternal fasting and intrafetal insulin

Silver¹,

Fowden²,

Taylor³

et al. 1994

Experimental Physiology

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SUMMARYBlood amino acids were measured in twelve chronically catheterized mares and fetuses between 250 and 310 days gestation. The concentrations of the majority of individual amino acids were similar in maternal and fetal arterial blood and no gestational changes were detected. Only methionine, phosphoserine, 3-methyl-histidine and glutamine were consistently higher in the fetus than the mare, whilst certain other amino acids were higher in the maternal blood. Fasting the mares for 36 h led to significant falls in plasma glucose and rises in urea and maternal free fatty acids (FFA). Small but significant decreases in a few amino acids were seen in both fetus and mother, with an overall amino acid fall of 15 % in the fetus and 13 % in the mare. Virtually all amino acids had risen to basal values by 6 h after feeding. Intrafetal insulin (1 i.u./kg i.v.) as a bolus caused a more dramatic fall in fetal glucose than fasting, with no change in the mare. There were also rapid decreases in many amino acids by 30 min post-insulin and by 2 h all but five amino acids had fallen significantly. There was a drop in total fetal blood amino acids of 29 %. These findings show that, in contrast to most other species studied, there is no overall feto-maternal gradient in blood amino acids in the mare, and that fasting leads to small falls in amino acid concentration, whereas intrafetal insulin induces a severe hypoglycaemia with dramatic decreases in almost all amino acids and no change in urea, suggesting a direct anabolic effect of insulin on fetal tissues.

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Placental transfer and fetal uptake of amino acids in the pregnant ewe

Cited by 41 publications

References 26 publications

Umbilical uptake of amino acids in the unstressed fetal lamb.

Umbilical uptake of amino acids in the unstressed fetal lamb.

The influence of intra-uterine surgery and of fetal intravenous nutritional supplements ‘in utero’ on plasma free amino acid homeostasis in the pregnant ewe

Blood amino acids in the pregnant mare and fetus: the effects of maternal fasting and intrafetal insulin

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