Free amino acids of normal and abnormal human placenta

Pearse, Warren H.; Sornson, Halvor C.

doi:10.1016/0002-9378(69)90005-2

Cited by 33 publications

(4 citation statements)

References 7 publications

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“…The parenchyma: foetal plasma gradient indicates the normally occurring downhill gradient between the placenta and foetal plasma. The high concentration of the free amino acids in the placental parenchyma agrees with the findings of Pearse & Sornson (1969) in human placental tissue and by Ryan & Carver (1966) for human foetal liver, in which the concentrations were greater than in the maternal liver. High concentrations of the metabolite glutamine, and the straight chain neutral amino acids, in comparison with the branched chain neutral and basic acids is characteristic of intracellular free amino acid levels generally.…”

Section: Discussionsupporting

confidence: 87%

Net placental transfer of free amino acids against varying concentrations

Hill¹,

Young²

1973

The Journal of Physiology

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SUMMARY1. The patterns of the free plasma amino acids in the pregnant guineapig and her foetuses, near term, are described. The concentration of each amino acid was higher in the foetal plasma than in the maternal. The foetal: maternal gradients (F: M) varied for each amino acid; the straight chain amino acids had the highest F: M ratios.2. Net transfer of endogenous plasma amino acids, from the maternal circulation across the placental membrane, was studied. The foetus was removed and the foetal placenta perfused in 8itu via the umbilical arteries, with an artificial fluid containing varying concentrations of amino acids.3. All the amino acids, both essential and non-essential, could be transferred from the maternal to the foetal circulation against the F: M gradients. With 'closed circuit' perfusion, this transport increased the concentration of total amino N in the perfusate until it was twice that of the normal F: M gradient of 5. The concentrations of the individual amino acids was increased to 1*7-4*2 times those normally present in foetal plasma, and the final values reached were similar to the concentrations of free amino acid found in placental tissue.4. The umbilical vein-artery differences were small, with the placenta perfused 'open circuit' in the steady state, using physiological flow rates and amino acid concentrations. The average net placental transfer of amino N found was 1*14 m-mole min-. This is about 60 % ofthe calculated net rate of accumulation of N by the 60 g guinea-pig foetus.5. The influence of foetal placental perfusion concentration on transfer was small but significant. In the steady state, the transfer of amino N, and each individual amino acid, was found to be inversely proportional to the concentrations in the perfusate when the placenta was perfused 'open circuit'. The slopes of the regression of transfer on concentration had an average value of 0-13 n-mole min' g-1 per 4amole. No significant difference in the slopes was found between the three amino acid transport groups.

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Section: Discussionsupporting

confidence: 87%

Net placental transfer of free amino acids against varying concentrations

Hill¹,

Young²

1973

The Journal of Physiology

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“…The concentration o f these nutrients have been mea sured, although less frequently in the amniotic fluid (13,20) and in the placental tissue (18). From these studies it has been concluded that transport of amino acids from mother to fetus is an active process (6,14) in which the placenta plays the role o f a selective biochemical system for the regulation of the amino acid transport.…”

mentioning

confidence: 99%

Amino Acid Pools in the Feto-Maternal System

et al. 1976

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The determinations of the amino acid pools, including tryptophan (by fluorescence spectrometry), in the arterial and venous blood of the mother, the arterial and venous blood of the fetus (cord blood), the amniotic fluid and the placenta was done in eight women at the moment of delivery. Only nine amino acids (asp, try, met, phe, ser, cys, lys, gly, thr) were significantly retained and four (arg, glu, pro and glu-NH₂) were significantly released by the fetal tissues. In contrast with this behavior most amino acids were retained by the maternal tissue, try, phe and hist showing the highest retention. When the amino acids are grouped as essential and nonessentials, the maternal tissues retained both categories without apparent discrimination, while the fetal tissues retained essential amino acids preferentially. Our results emphasize the importance of the placenta as the regulating system of the fetal milieu under normal conditions. Thus human fetal blood levels of amino acids are patterned after the placental ones and not after the maternal values obtained at the same time. It is apparent that the placenta seems to function as a nonspecific retention filter for outgoing amino acids, but that its function is selective in respect to the release of amino acids into the fetal circulation.

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“…(4)). Thus, the concentrations of amino acids in the cytosol of the syncytiotrophoblast are much higher than those in both maternal and fetal blood [80,81]. The asymmetric distribution of amino acid transporters between the two syncytiotrophoblast plasma membranes, with secondary active transport systems primarily expressed in the MVM, is critical in order to generate a net flux of amino acids from mother to fetus.…”

Section: Amino Acidsmentioning

confidence: 99%

The Role of Trophoblast Nutrient and Ion Transporters in the Development of Pregnancy Complications and Adult Disease

Jansson¹,

Myatt²,

Powell³

2009

CVP

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Intrauterine growth restriction (IUGR) and fetal overgrowth occur in 15% of all pregnancies and lead to the delivery of a baby with an abnormally low or high birth weight, respectively. Both these conditions of pathological fetal growth increase the risk for perinatal complications and predispose the baby for the development of cardiovascular disease and diabetes in childhood and later in life. Fetal growth is closely related to the capacity of the placenta to transport nutrients and ions, which is dependent of the expression and activity of specific transporter proteins in the plasma membrane of the syncytiotrophoblast, the transporting epithelium of the human placenta. In human IUGR, some trophoblast nutrient and ion transporters are down regulated, whereas fetal overgrowth is associated with an up-regulation of transporters for amino acids and glucose in the placental barrier. Experimental studies have provided evidence to suggest that these changes in placental transport capacity constitute a direct cause of altered fetal growth. Therefore, regulation of placental nutrient transporters play a critical role in determining fetal growth and development, as well as the future health of the baby. This review is focused on the human and (i) summarizes the evidence that changes in the activity and expression of trophoblast nutrient and ion transporters play a central role in determining fetal growth, (ii) discusses the molecular mechanisms regulating trophoblast transporters, and (iii) highlights the implications of these findings for the development of pregnancy complications and fetal programming of cardiovascular and metabolic disease.

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Free amino acids of normal and abnormal human placenta

Cited by 33 publications

References 7 publications

Net placental transfer of free amino acids against varying concentrations

Net placental transfer of free amino acids against varying concentrations

Amino Acid Pools in the Feto-Maternal System

The Role of Trophoblast Nutrient and Ion Transporters in the Development of Pregnancy Complications and Adult Disease

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