Technical Note: Can tail arterial or tail venous blood represent external pudic arterial blood to measure amino acid uptake by mammary gland of cows?

Five multiparous Saanen goats in late lactation were infused with 35S-cysteine into the mammary gland via the external pudic artery. A further 2 goats were infused with 35S-methionine via the same artery and later with 35S-methionine into the jugular vein. Total uptake of cysteine from the arterial blood supply by the mammary gland was approximately 6% of the 35S-cysteine flux past the gland, whereas uptake of methionine was 30–40%. Total mammary uptake of cysteine was also lower than that of methionine when expressed as a percentage of whole body utilisation (6.5 and 14%, respectively). The uptake from the blood did not account for output in the milk for either cysteine or methionine. Both amino acids were highly conserved by the gland as shown by little release of any degraded constitutive protein amino acids and no evidence of oxidation products of either cysteine or methionine being released into the blood. Comparison of 35S activity in the milk from the infused and non-infused sides of the gland showed up to 10% trans-sulfuration of methionine to cysteine within the gland, none of which was exported in the venous drainage. Total ATP production by one side of the gland was 12.1 mol/day or 13 mmol/min.kg mammary tissue, of which 15% was required for gland protein synthesis. The experimental measurements from both the cysteine and methionine infusions were used to solve a model of gland amino acid uptake and partitioning. Modelling radioactivity of both amino acids in the blood, intracellular free pool, and milk protein suggested that a single intracellular pool cannot be the only source of amino acid for protein synthesis. The model also provides support for the hypothesis that a significant proportion of the uptake of at least some amino acids by the mammary gland is from intracellular hydrolysis of extracellularly derived peptides.

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Control of amino acid uptake by the lactating mammary gland of the rat

Biochemical Society Transactions ◽

10.1042/bst0090392 ◽

1981 ◽

Vol 9 (5) ◽

pp. 392-392 ◽

Cited By ~ 2

Author(s):

JUAN R. VIÑA ◽

JUAN B. MONTORO ◽

INMACULADA R. PUERTES ◽

JOSE VIÑA

Keyword(s):

Mammary Gland ◽

Amino Acid ◽

Amino Acid Uptake ◽

Acid Uptake ◽

Lactating Mammary Gland

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Effects of chronic ethanol treatment on amino acid uptake and enzyme activities in the lactating rat mammary gland

Life Sciences ◽

10.1016/0024-3205(87)90084-1 ◽

1987 ◽

Vol 40 (18) ◽

pp. 1745-1749 ◽

Cited By ~ 11

Author(s):

O. Viñas ◽

S. Vilaró ◽

E. Herrera ◽

X. Remesar

Keyword(s):

Mammary Gland ◽

Amino Acid ◽

Enzyme Activities ◽

Amino Acid Uptake ◽

Chronic Ethanol ◽

Acid Uptake ◽

Ethanol Treatment ◽

Rat Mammary Gland

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Effects of hormones on protein and amino acid metabolism in mammary-gland explants of mice

Biochemical Journal ◽

10.1042/bj1580355 ◽

1976 ◽

Vol 158 (2) ◽

pp. 355-359 ◽

Cited By ~ 12

Author(s):

L D Anderson ◽

J A Rillema

Keyword(s):

Mammary Gland ◽

Amino Acid ◽

Protein Biosynthesis ◽

Insulin Response ◽

Exposure Period ◽

Amino Acid Uptake ◽

Isobutyric Acid ◽

Leucine Incorporation ◽

Acid Uptake ◽

Pregnant Mice

The effects of insulin, cortisol and prolactin on amino acid uptake and protein biosynthesis were determined in mammary-gland explants from mid-pregnant mice. Insulin stimulated [3H]leucine incorporation into protein within 15 min of adding insulin to the incubation medium. Insulin also had a rapid stimulatory effect on the rate of aminoiso[14C]butyric acid uptake, but it had no effect on the intracellular accumulation of [3H]leucine. Cortisol inhibited the rate of [3H]leucine incorporation into protein during the initial 4h of incubation, but it had no effect at subsequent times. [3H]Leucine uptake was unaffected by cortisol, but amino[14C]isobutyric acid uptake was inhibited after a 4h exposure period to this hormone. Prolactin stimulated the rate of [3H]leucine incorporation into protein when tissues were exposed to this hormone for 4h or more; up to 4h, however, no effect of prolactin was detected. At all times tested, prolactin had no effect on the uptake of either amino[14C]isobutyric acid or [3H]leucine. Incubation with actinomycin D abolished the prolactin stimulation of protein biosynthesis, but this antibiotic did not affect the insulin response. A distinct difference in the mechanism of action of these hormones on protein biosynthesis in the mammary gland is thus apparent.

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Isotope dilution models for partitioning amino acid uptake by the liver, mammary gland and hindlimb tissues of ruminants.

Modelling nutrient utilization in farm animals. ◽

10.1079/9780851994499.0353 ◽

2009 ◽

pp. 353-360

Author(s):

L. A. Crompton ◽

J. France ◽

B. J. Bequette ◽

J. A. Maas ◽

M. D. Hanigan ◽

...

Keyword(s):

Mammary Gland ◽

Amino Acid ◽

Isotope Dilution ◽

Amino Acid Uptake ◽

Acid Uptake

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

Journal of Dairy Research ◽

10.1017/s002202990001685x ◽

1979 ◽

Vol 46 (1) ◽

pp. 59-67 ◽

Cited By ~ 6

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.

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