scholarly journals Effect of starvation and refeeding on amino acid uptake by mammary gland of the lactating rat. Role of ketone bodies

1983 ◽  
Vol 216 (2) ◽  
pp. 343-347 ◽  
Author(s):  
J R Viña ◽  
I R Puertes ◽  
J B Montoro ◽  
J Viña
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Ketone Bodies ◽  
Total Concentration ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Arterial Concentration ◽  
Blood Ketone Bodies

Arteriovenous differences of amino acids across the mammary glands of lactating rats are diminished when the rats are starved for 24 h. When 24 h-starved rats were refed for 2 1/2 h, the arteriovenous differences of amino acids returned to values similar to those found in well-fed rats. In order to find a possible explanation for these rapid changes, we tested the effect of ketone bodies on amino acid uptake by the gland. At 5 min after injection of acetoacetate to fed rats, when the total concentration of ketone bodies in blood was similar to that found in starvation, the uptake of amino acids by the mammary gland was similar to that found after starvation, i.e. lower than in fed rats. However, 30 min after administration of acetoacetate, when the arterial concentration of ketone bodies had returned to values similar to those in fed rats, the arteriovenous differences of amino acids were similar to those found in fed rats. We conclude that the changes in blood ketone bodies may be responsible, at least in part, for the changes in amino acid uptake that occur in starvation and in the starvation—refeeding transition.

Gamma-Glutamyl-Amino Acids as Signals for the Hormonal Regulation of Amino Acid Uptake by the Mammary Gland of the Lactating Rat

Neonatology ◽  
1985 ◽  
Vol 48 (4) ◽  
pp. 250-256 ◽  
Author(s):  
Juan R. Viña ◽  
Inmaculada R. Puertes ◽  
Juan B. Montoro ◽  
Guillermo T. Saez ◽  
José Viña
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Hormonal Regulation ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Gamma Glutamyl

Effects of intramammary arterial infusion of essential amino acids in the lactating goat

1974 ◽  
Vol 41 (1) ◽  
pp. 101-109 ◽  
Author(s):  
J. L. Linzell ◽  
T. B. Mepham
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Milk Protein ◽  
Amino Acid Uptake ◽  
Essential Amino Acids ◽  
Acid Uptake ◽  
Lactating Goats ◽  
Arterial Concentration ◽  
Arterial Plasma ◽  
Amino Acid Concentrations

SummaryExperiments were performed on 3 lactating goats, in which mammary arterial plasma amino-acid concentrations were elevated by the infusion of a solution of essential amino-acids into the carotid artery supplying a transplanted mammary gland. In 2 experiments there were marked elevations in the arterial concentrations of most essential amino acids, but in one case only did this result in significantly increased uptake of amino acids by the gland, the arterio-venous difference being significantly correlated with arterial concentration for all except one amino acid. In the experiment in which increased amino-acid uptake was observed, infusion also resulted in a significantly increased milk yield and increased milk protein yield. The results are discussed in relation to data from other laboratories and lead to the suggestion that milk protein synthesis may be limited by the availability of either methionine or tryptophan.

Amino acid uptake by the fetal ovine hindlimb under normal and euglycemic hyperinsulinemic states

1994 ◽  
Vol 266 (1) ◽  
pp. E72-E78 ◽  
Author(s):  
R. B. Wilkening ◽  
D. W. Boyle ◽  
C. Teng ◽  
G. Meschia ◽  
F. C. Battaglia
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Total Nitrogen ◽  
Nitrogen Uptake ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Arterial Concentration ◽  
Significant Uptake ◽  
Fetal Organs ◽  
Fetal Uptake

As part of an effort to establish the contribution of different fetal organs to fetal amino acid metabolism, we measured in nine sheep fetuses the uptake of 27 amino acids by the hindlimb under normal conditions and conditions by euglycemic hyperinsulinemia. The fetal hindlimb is representative of nonvisceral tissues, which in the mature fetus account for approximately 70% of fetal weight and 30% of fetal O2 consumption. In the normal condition, there was a significant uptake of 21 amino acids for a net total nitrogen uptake of 132 +/- 21 mg N.day-1 x 100 g-1. The amino acids taken up by the fetal limb included alanine and glutamine. In addition, the fetal limb had significant glutamate and serine uptakes. Because glutamate flows from fetus to placenta and there is no fetal uptake of maternal serine, this indicates production and interorgan transport of these amino acids within the fetus. Insulin infusion significantly decreased the arterial concentration of every amino acid with the exception of cystathionine and significantly increased limb blood flow and glucose uptake. It significantly increased the limb uptake of alanine, asparagine, glycine, isoleucine, methionine, and tyrosine, decreased the uptake of aspartate, and produced no significant change in the net total nitrogen uptake, which remained similar to control (137 +/- 16 mg N.day-1 x 100 g-1).

Effects of increased supply of essential amino acids on the metabolism of the isolated perfused guinea-pig mammary gland

1979 ◽  
Vol 46 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Andrew R. Peters ◽  
Stephen Alexandrov ◽  
T. Ben Mepham
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Guinea Pig ◽  
Amino Acid Uptake ◽  
Essential Amino Acids ◽  
Acid Uptake ◽  
Isoleucine Leucine ◽  
Group 1

SUMMARYThe effects of high rates of infusion of essential amino acids on amino acid uptake by the isolated perfused guinea-pig mammary gland were studied. Infusion of methionine, tyrosine, phenylalanine, histidine and tryptophan (designated group 1) resulted in significant increases in the uptakes of tyrosine, phenylalanine and histidine. Methionine, tryptophan and other essential amino acids were not significantly affected. Infusion of threonine, valine, isoleucine, leucine, lysine and arginine (designated group 2) resulted in significant increases in uptake of all these amino acids. Group 1 amino acid uptake was not significantly affected. Infusion of all the essential amino acids (i.e. groups 1 and 2 together) resulted in significant increases in all their uptakes. Using as index ‘the predicted rate of protein synthesis’, infusion of group 1 and 2 together led to an apparent 27% increase in protein synthesis. The above results are discussed in relation to the control of milk protein synthesis by limiting essential amino acids.

Are the γ-glutamyl-amino acids signals for the amino acid uptake by lactating mammary gland?

1986 ◽  
Vol 14 (2) ◽  
pp. 311-312 ◽  
Author(s):  
JUAN R. VIÑA ◽  
INMACULADA R. PUERTES ◽  
JUAN B. MONTORO ◽  
ARGIMIRO RODRIGUEZ ◽  
JOSÉ VIÑA
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Lactating Mammary Gland

scholarly journals Role of prolactin in amino acid uptake by the lactating mammary gland of the rat

FEBS Letters ◽  
1981 ◽  
Vol 126 (2) ◽  
pp. 250-252 ◽  
Author(s):  
José Viña ◽  
Inmaculada R. Puertes ◽  
Guillermo T. Saez ◽  
Juan R. Viña
Keyword(s):  
Mammary Gland ◽  
Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Lactating Mammary Gland

scholarly journals Effect of premature weaning on amino acid uptake by the mammary gland of lactating rats

1981 ◽  
Vol 200 (3) ◽  
pp. 705-708 ◽  
Author(s):  
J R Viña ◽  
I R Puertes ◽  
J Viña
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Amino Acid Uptake ◽  
Mammary Glands ◽  
Acid Uptake ◽  
Gamma Glutamyltransferase ◽  
Gamma Glutamyl ◽  
Lactating Mammary Gland

1. Arteriovenous differences of amino acids across the lactating mammary gland were measured in normal rats and weaned for 4, 5 and 24h. 2. Uptake of amino acids by mammary glands of rats weaned for 5h or more was significantly lower than that of controls. This was not reversed by injection of prolactin. 3. By using ‘unilaterally weaned’ rats we showed that milk accumulation plays an important role in amino acid uptake by mammary gland. 4. gamma-Glutamyltransferase activity was significantly lower in ‘weaned’ glands than in ‘normal’ glands. This provides further support for the hypothesis of the function of the gamma-glutamyl cycle in the mammary gland in vivo.

scholarly journals Involvement of γ-glutamyltransferase in amino-acid uptake by the lactating mammary gland of the rat

1981 ◽  
Vol 194 (1) ◽  
pp. 99-102 ◽  
Author(s):  
J Viña ◽  
I R Puertes ◽  
J M Estrela ◽  
J R Viña ◽  
J L Galbis
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Reduced Glutathione ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Gamma Glutamyltransferase ◽  
Lactating Mammary Gland ◽  
High Concentrations

1. Arteriovenous differences of amino acids across the lactating mammary gland have been measured in normal rats and in rats injected with serine–borate (an inhibitor of gamma-glutamyltransferase). 2. Comparison of the arteriovenous differences show that gamma-glutamyltransferase is involved in amino-acid uptake by the gland. 3. Reduced-glutathione content of isolated acini incubated with high concentrations of amino acids was lower than that of the controls. 4. High concentrations of amino acids had no effect on reduced-glutathione content of isolated acini when serine–borate was added to the incubation medium. 5. The findings provide evidence for the functioning of the gamma-glutamyl cycle in the lactating mammary gland in vivo.

scholarly journals Action of growth hormone in vitro on the net uptake and incorporation into protein of amino acids in muscle from intact rabbits given protein-deficient diets

1976 ◽  
Vol 35 (1) ◽  
pp. 1-10 ◽  
Author(s):  
M. R. Turner ◽  
P. J. Reeds ◽  
K. A. Munday
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Amino Acid ◽  
De Novo ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Amino Acid Incorporation ◽  
Acid Incorporation

1. Net amino acid uptake, and incorporation into protein have been measured in vitro in the presence and absence of porcine growth hormone (GH) in muscle from intact rabbits fed for 5 d on low-protein (LP), protein-free (PF) or control diets.2. In muscle from control and LP animals GH had no effect on the net amino acid uptake but stimulated amino acid incorporation into protein, although this response was less in LP animals than in control animals.3. In muscle from PF animals, GH stimulated both amino acid incorporation into protein and the net amino acid uptake, a type of response which also occurs in hypophysectomized animals. The magnitude of the effect of GH on the incorporation of amino acids into protein was reduced in muscle from PF animals.4. The effect of GH on the net amino acid uptake in PF animals was completely blocked by cycloheximide; the uptake effect of GH in these animals was dependent therefore on de novo protein synthesis.5. It is proposed that in the adult the role of growth hormone in protein metabolism is to sustain cellular protein synthesis when there is a decrease in the level of substrate amino acids, similar to that which occurs during a short-term fast or when the dietary protein intake is inadequate.

The uptake of amino acids by mouse cells (strain LS) during growth in batch culture and chemostat culture: the influence of cell growth rate

1967 ◽  
Vol 168 (1013) ◽  
pp. 421-438 ◽  
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Amino Acid ◽  
Cell Growth ◽  
Glutamic Acid ◽  
Batch Culture ◽  
Amino Acid Uptake ◽  
Essential Amino Acids ◽  
Growth Yields ◽  
Acid Uptake

The uptake of thirteen essential amino acids by mouse LS cells in suspension culture was determined by bacteriological assay methods. Chemostat continuous-flow cultures were used to determine the effect of different cell growth rates on the quantitative amino acid requirements for growth. The growth yields of the cells ( Y = g cell dry weight produced/g amino acid utilized) were calculated for each of the essential amino acids. A mixture of the non-essential amino acids, serine, alanine and glycine increased the cell yield from the essential amino acids. The growth yields from nearly all the essential amino acids in batch culture were increased when glutamic acid was substituted for the glutamine in the medium. The growth yields from the amino acids in batch culture were much less at the beginning than at the end of the culture. The highest efficiencies of conversion of amino acids to cell material were obtained by chemostat culture. When glutamic acid largely replaced the glutamine in the medium the conversion of amino acid nitrogen to cell nitrogen was 100 % efficient (that is, the theoretical yield was obtained) at the optimum growth rate (cell doubling time, 43 h). The maximum population density a given amino acid mixture will support can be calculated from the data. It is concluded that in several routinely used tissue culture media the cell growth is limited by the amino acid supply. In batch culture glutamine was wasted by (1) its spontaneous decomposition to pyrrolidone carboxylic acid and ammonia, and (2) its enzymic breakdown to glutamic acid and ammonia, but also glutamine was used less efficiently than glutamic acid. Study of the influence of cell growth rate on amino acid uptake rates per unit mass of cells indicated that a marked change in amino acid metabolism occurred at a specific growth rate of 0.4 day -1 (cell doubling time, 43 h). With decrease in specific growth rate below 0.4 day -1 there was a marked stimulation of amino acid uptake rate per cell and essential amino acids were consumed increasingly for functions other than synthesis of cell material.

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