scholarly journals Metabolism of urea in late pregnancy and the possible contribution of amino acid carbon to glucose synthesis in sheep

1970 ◽  
Vol 24 (4) ◽  
pp. 905-915 ◽  
Author(s):  
J. V. Nolan ◽  
R. A. Leng
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Late Pregnancy ◽  
Pool Size ◽  
Entry Rate ◽  
Plasma Urea ◽  
Upper Limit ◽  
Pregnant Sheep ◽  
Potential Availability ◽  
Glucose Synthesis

1. Metabolism of urea in non-pregnant and pregnant sheep (1–25 d from term) has been examined. Injections of [14C]urea were used to estimate urea entry rate, urea pool size and urea space in sheep given 1000 g of a diet of equal parts of crushed oats and chaffed lucerne hay (daya) and in the same sheep 4 d after the ration had been reduced to 250 g (dayb).2. On both experimental days (aandb), mean pool size was greater (14% on day α, 29% on dayb) and urea space was greater (54% on day α, 24% on dayb) in pregnant animals than in non-pregnant animals; mean plasma urea concentrations were lower (35%) in the pregnant animals on day a but were not significantly different on dayb.3. The entry rate of urea was similar in all the animals on daya, but was significantly higher (34%) in pregnant than in non-pregnant animals on dayb. There was a significant decrease in urea entry rate in both pregnant (33%) and non-pregnant (86%) animals on dayb.4. The rate of excretion of urea was lower (26% on daya, 35% on dayb) in pregnant animals, indicating a higher (31% on day α, 40% on dayb) rate of degradation of urea in the digestive tract of pregnant as compared with non-pregnant sheep.5. Measurements of urea entry rate have been used to calculate the upper limit of amino acid deamination in pregnant and non-pregnant sheep, and this has been used as an indication of the potential availability of amino acid carbon for glucose synthesis. It is suggested that, at a maximum, amino acids may have contributed the carbon required for 63 g/d and 52 g/d of glucose on daysaandbrespectively.

THE EFFECT OF BETAMETHASONE ON GLUCOSE PRODUCTION AND ON GLUCONEOGENESIS FROM AMINO ACIDS IN SHEEP

1974 ◽  
Vol 60 (3) ◽  
pp. 455-461 ◽  
Author(s):  
P. E. B. REILLY ◽  
E. J. H. FORD
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Glucose ◽  
Intramuscular Injection ◽  
Significant Proportion ◽  
Glucose Production ◽  
Entry Rate ◽  
Steroid Administration ◽  
Single Intramuscular Injection ◽  
Mean Glucose

SUMMARY Primed continuous infusions of tracer amounts of [U-14C]glucose and of [U-14C]labelled mixed amino acids were used to measure plasma glucose and amino acid entry rates and to obtain an index of the incorporation of amino acid carbon into glucose by sheep before and 24 h after a single intramuscular injection of betamethasone. Maximum hyperglycaemia occurred 24 h after administration of the steroid, but there was no significant change in arterial amino acid concentration. Mean glucose entry rate was significantly raised 24 h after steroid administration. The rate of incorporation of amino acid carbon into glucose also increased significantly. The increases in plasma glucose concentration and in glucose entry confirm the authors' previous results. The results also indicate that a significant proportion of the additional glucose entry is synthesized from amino acid carbon.

Wool growth and sulfur amino acid entry rate in sheep fed roughage based diets supplemented with bentonite and sulfur amino acids

1989 ◽  
Vol 40 (4) ◽  
pp. 889 ◽  
Author(s):  
PD Fenn ◽  
RA Leng
Keyword(s):  
Amino Acids ◽  
Drinking Water ◽  
Amino Acid ◽  
Continuous Infusion ◽  
Basal Diet ◽  
Sulfur Amino Acid ◽  
Sulfur Amino Acids ◽  
Entry Rate ◽  
Wool Growth ◽  
Water Supplementation

In two experiments, sheep were offered a roughage-based diet supplemented with either cysteine or bentonite as a solid, or bentonite, cysteine or methionine added to their drinking water. Supplementation with cysteine as a solid had no effect on wool growth, while supplementation via drinking water had no effect on wool growth or cysteine entry rate into the blood. Supplementation with methionine via drinking water increased the entry rate of methionine into blood by 69% (P< 0.05) as measured by a continuous infusion of [35S]-methionine. This coincided with subsequent increases in wool growth of 16% (P< 0.05) compared to sheep fed a basal diet alone. Compared with the basal diet alone, supplementation with 30 g/day bentonite as a dry powder or 60 g/day as a suspension in drinking water increased wool growth by 19 and 20% respectively. Bentonite given as sole supplement did not increase the entry rate of either cysteine or methionine into the blood of sheep. When bentonite and sulfur amino acids were complexed or mixed, wool growth was not increased above that for bentonite or the amino acid alone.

scholarly journals Amino Acid Transport into Cultured McCoy Cells Infected with Chlamydia trachomatis

2000 ◽  
Vol 68 (9) ◽  
pp. 5439-5442 ◽  
Author(s):  
Angela Harper ◽  
Christopher I. Pogson ◽  
John H. Pearce
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chlamydia Trachomatis ◽  
Amino Acid Transport ◽  
Equilibrium Concentration ◽  
Transport Systems ◽  
Acid Transport ◽  
Entry Rate ◽  
Great Capacity ◽  
Cationic Amino Acids

ABSTRACT Amino acid transport into McCoy cells infected with strains representative of the two major biovars of Chlamydia trachomatis has been studied to determine if uptake is increased during infection. Preliminary work suggested that the transport systems L, A/ASC (for neutral amino acid transport), N (for transport of Asn, Gln, and His) and y+ (for cationic amino acids) were present in McCoy cells. With lymphogranuloma venereum biovar strain 434, little difference in the influx of representative amino acids Trp, His, and Lys or the analogue 2-aminoisobutyric acid (AIB) was observed during infection. With trachoma biovar strain DK20, a small increase in the initial entry rate and equilibrium concentration of each amino acid was found. McCoy cells appear to have great capacity for concentrating amino acids, which might obviate the need for transport induction by chlamydiae under conditions favoring the growth of infectious organisms.

Changes in plasma amino acid patterns and wool growth in response to abomasal injections of amino acids during late pregnancy and early lactation

1993 ◽  
Vol 44 (5) ◽  
pp. 959 ◽  
Author(s):  
CA Stewart ◽  
DG Masters ◽  
IH Williams ◽  
PJ Connell
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Late Pregnancy ◽  
Early Lactation ◽  
Growth Responses ◽  
Specific Amino Acid ◽  
Protein Deposition ◽  
Wool Growth ◽  
Limiting Amino Acids ◽  
Sulfur Containing

Provision of sulfur-containing amino acids into the abomasum has increased wool production in non-reproducing sheep and, on the basis of such studies, they have generally been considered as the primary limiting nutrients for wool growth. The specific amino acid needs of reproducing ewes were investigated in the current study. Three groups of pregnant ewes were fitted with temporary abomasal fistulae. For the last 3-4 weeks of pregnancy and the first 3 weeks of lactation, solutions containing sodium hydroxide (as a carrier) or methionine or a mixture of valine, arginine, lysine and threonine (VALT) were injected into the abomasum twice per day. The injection of methionine did not increase protein deposition during pregnancy; this was indicated by the failure of the treatment to lower the concentration of other amino acids in plasma, or increase liveweight, lamb birth weight or wool growth. Responses in early lactation were different with the methionine injected sheep having a lower concentration of free lysine, valine, alanine and serine in plasma, indicating an increased rate of protein deposition, and a faster growth rate in the ewes. Injections of VALT caused a decrease in the concentration of cystine and methionine in plasma and depressed wool growth and tensile strength. Theresults indicate that a lack of methionine was not limiting protein deposition during late pregnancy, but may have been during early lactation. Valine, arginine, lysine and threonine were not the primary limiting amino acids in late pregnancy or early lactation.

scholarly journals The effect of glucose infusion on the plasma free amino acids in sheep

1975 ◽  
Vol 34 (3) ◽  
pp. 375-382 ◽  
Author(s):  
N. W. Offer ◽  
M. V. Tas ◽  
R. F. E. Axford ◽  
R. A. Evans
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Late Pregnancy ◽  
Essential Amino Acids ◽  
Glucose Infusion ◽  
Pregnant Sheep ◽  
Before And After ◽  
Effect Of Glucose ◽  
Plasma Free Amino Acids

1. Glucose in solution in saline, or saline alone, was administered to a group of twenty ewes during late pregnancy and again after lambing. Sequential blood samples were taken before and after the infusion and the concentration of plasma free amino acids was determined.2. The effect of glucose was to reduce the concentrations of all amino acids except alanine. The reduction was greatest for tryptophan in the pregnant sheep, but this amino acid showed no significant change in the lactating animals.3. An attempt to rank the amino acids on the basis of their response to glucose infusion indicated that, with the exception of tryptophan for the preparturient ewes, groups of essential amino acids could not be distinguished from each other. These groups were, for the preparturient sheep, valine, leucine, phenylalanine and isoleucine, and for the postparturient animals, isoleucine, lysine, methionine, valine and phenylalanine.

Amino acid nutrition of the lactating sow: limitation by indispensable amino acids

1984 ◽  
Vol 38 (2) ◽  
pp. 263-270 ◽  
Author(s):  
R. Wilkinson ◽  
D. J. A. Cole ◽  
D. Lewis
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Control Diet ◽  
Latin Square ◽  
Basal Diet ◽  
Plasma Urea ◽  
Synthetic Amino Acids ◽  
Dietary Amino Acid ◽  
Indispensable Amino Acids ◽  
Soya Bean Meal

ABSTRACTIn the first of two experiments of 6 × 6 Latin-square design a diet of barley, soya bean meal and fish meal, known to give an adequate lysine intake (56 g/day) at the level of feeding adopted, was diluted with maize starch to give crude protein intakes ranging between 448 and 923 g/day but with the lysine intake held constant by using synthetic lysine in the diets. The diets were given to sows suckling ten piglets between days 12 and 30 of lactation. Dietary amino acid adequacy was assessed by changes in plasma urea, urinary urea, urinary nitrogen and plasma amino acid concentrations. The dietary amino acid supply became limiting with a protein intake of approximately 730 g/day. In the second experiment, a diet of similar composition was used with varying additions of synthetic threonine, methionine, isoleucine and tryptophan: the control diet contained all the synthetic amino acids added, the basal diet none and the other diets were formed by adding groups of three out of the four synthetic amino acids. On the basis of some of the variables studied, it was concluded that, for this diet, threonine was the limiting amino acid after lysine.

scholarly journals Prolonged maternal amino acid infusion in late-gestation pregnant sheep increases fetal amino acid oxidation

2009 ◽  
Vol 297 (3) ◽  
pp. E638-E646 ◽  
Author(s):  
Paul J. Rozance ◽  
Michelle M. Crispo ◽  
James S. Barry ◽  
Meghan C. O'Meara ◽  
Mackenzie S. Frost ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Supplementation ◽  
Late Gestation ◽  
Acid Oxidation ◽  
Leucine Incorporation ◽  
Oxygen Utilization ◽  
Amino Acid Oxidation ◽  
Amino Acid Infusion ◽  
Pregnant Sheep

Protein supplementation during human pregnancy does not improve fetal growth and may increase small-for-gestational-age birth rates and mortality. To define possible mechanisms, sheep with twin pregnancies were infused with amino acids (AA group, n = 7) or saline (C group, n = 4) for 4 days during late gestation. In the AA group, fetal plasma leucine, isoleucine, valine, and lysine concentrations were increased ( P < 0.05), and threonine was decreased ( P < 0.05). In the AA group, fetal arterial pH (7.365 ± 0.007 day 0 vs. 7.336 ± 0.012 day 4, P < 0.005), hemoglobin-oxygen saturation (46.2 ± 2.6 vs. 37.8 ± 3.6%, P < 0.005), and total oxygen content (3.17 ± 0.17 vs. 2.49 ± 0.20 mmol/l, P < 0.0001) were decreased on day 4 compared with day 0. Fetal leucine disposal did not change (9.22 ± 0.73 vs. 8.09 ± 0.63 μmol·min−1·kg−1, AA vs. C), but the rate of leucine oxidation increased 43% in the AA group (2.63 ± 0.16 vs. 1.84 ± 0.24 μmol·min−1·kg−1, P < 0.05). Fetal oxygen utilization tended to be increased in the AA group (327 ± 23 vs. 250 ± 29 μmol·min−1·kg−1, P = 0.06). Rates of leucine incorporation into fetal protein (5.19 ± 0.97 vs. 5.47 ± 0.89 μmol·min−1·kg−1, AA vs. C), release from protein breakdown (4.20 ± 0.95 vs. 4.62 ± 0.74 μmol·min−1·kg−1), and protein accretion (1.00 ± 0.30 vs. 0.85 ± 0.25 μmol·min−1·kg−1) did not change. Consistent with these data, there was no change in the fetal skeletal muscle ubiquitin ligases MaFBx1 or MuRF1 or in the protein synthesis regulators 4E-BP1, eEF2, eIF2α, and p70S6K. Decreased concentrations of certain essential amino acids, increased amino acid oxidation, fetal acidosis, and fetal hypoxia are possible mechanisms to explain fetal toxicity during maternal amino acid supplementation.

Reciprocal inhibition of umbilical uptake within groups of amino acids

2004 ◽  
Vol 286 (3) ◽  
pp. E376-E383 ◽  
Author(s):  
Maciej Jóźwik ◽  
Cecilia Teng ◽  
Randall B. Wilkening ◽  
Giacomo Meschia ◽  
Frederick C. Battaglia
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Reciprocal Inhibition ◽  
Essential Amino Acids ◽  
Maternal Plasma ◽  
Pregnant Sheep ◽  
Amino Acid Mixtures ◽  
Uptake Data ◽  
Inhibitory Amino Acids ◽  
Inhibitory Interactions

Eight pregnant sheep were infused with two amino acid mixtures of different composition: essential amino acids only and the essentials plus some of the nonessentials. Uterine and umbilical uptakes of amino acids were measured before and during infusion. For most of the amino acids, the infusion increased both maternal plasma concentration and umbilical uptake. However, depending on the infusate composition, the increase in maternal concentration of some amino acids was associated with no change or a significant reduction in umbilical uptake. Data were pooled from this and other, similar studies to test the hypothesis that umbilical uptake of several amino acids can be inhibited by coinfused amino acids. The test consisted of fitting the data, by means of multiple regression analysis, to the linear transformation of a saturation kinetics equation in which uptake is assumed to depend on maternal arterial concentrations. The analysis showed significant inhibitory effects within the neutral essential amino acids group and within the lysine-arginine group, with no demonstrable interaction between the two groups. Uterine uptakes did not show clear evidence of saturability and inhibitory interactions, suggesting a large transport capacity and low transporter affinity on the maternal surface of the trophoblast. We conclude that the transport of any given amino acid from placenta to fetus is a function of both its own maternal concentration and the maternal concentration of inhibitory amino acids.

Beyond lipids, pharmacological PPARα activation has important effects on amino acid metabolism as studied in the rat

2007 ◽  
Vol 292 (4) ◽  
pp. E1157-E1165 ◽  
Author(s):  
Kashif Sheikh ◽  
Germán Camejo ◽  
Boel Lanne ◽  
Torbjörn Halvarsson ◽  
Marie Rydén Landergren ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Levels ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Body Weight Gain ◽  
Saturated Fat ◽  
Whole Body ◽  
Dna Arrays ◽  
Plasma Urea

PPARα agonists have been characterized largely in terms of their effects on lipids and glucose metabolism, whereas little has been reported about effects on amino acid metabolism. We studied responses to the PPARα agonist WY 14,643 (30 μmol·kg−1·day−1 for 4 wk) in rats fed a saturated fat diet. Plasma and urine were analyzed with proton NMR. Plasma amino acids were measured using HPLC, and hepatic gene expression was assessed with DNA arrays. The high-fat diet elevated plasma levels of insulin and triglycerides (TG), and WY 14,643 treatment ameliorated this insulin resistance and dyslipidemia, lowering plasma insulin and TG levels. In addition, treatment decreased body weight gain, without altering cumulative food intake, and increased liver mass. WY 14,643 increased plasma levels of 12 of 22 amino acids, including glucogenic and some ketogenic amino acids, whereas arginine was significantly decreased. There was no alteration in branched-chain amino acid levels. Compared with the fat-fed control animals, WY 14,643-treated animals had raised plasma urea and ammonia levels as well as raised urine levels of N-methylnicotinamide and dimethylglycine. WY 14,643 induced changes in a number of key genes involved in amino acid metabolism in addition to expected effects on hepatic genes involved in lipid catabolism and ketone body formation. In conclusion, the present results suggest that, in rodents, effects of pharmacological PPARα activation extend beyond control of lipid metabolism to include important effects on whole body amino acid mobilization and hepatic amino acid metabolism.

scholarly journals Foetal and maternal rates of urea production and disposal in well-nourished and undernourished sheep

1982 ◽  
Vol 48 (1) ◽  
pp. 49-58 ◽  
Author(s):  
J. C. Hodgson ◽  
D. J. Mellor ◽  
A. C. Field
Keyword(s):  
Live Weight ◽  
Close Correlation ◽  
Entry Rate ◽  
Jugular Veins ◽  
Plasma Urea ◽  
Indwelling Catheters ◽  
Dietary Nitrogen ◽  
Pregnant Sheep ◽  
Urea Production ◽  
Series Of Experiments

1. Five monotocous and twoditocous Scottish Blackface ewes with indwelling catheters in an umbilical artery and vein of one foetus only and in both maternal jugular veins were used.2. Experiments were conducted over a period of 2 d when [I4C]urea was infused intravenously over 9 h into either the mother or foetus, separate days being used for each infusion. Two series of experiments were completed, one in well-nourished and the other in undernourished sheep at 125–141) and 138–143 d of gestation respectively.3. Plasma urea specific radioactivities of the mother and infused foetus at plateau were used to determine the urea flux-rates within and between mother and foetus. The mean rate of foetal urea production (Ffo) was 1.45 and 1.63 mg/min per kg foetus in well-nourished and undernourished ewes respectively. The corresponding rates of maternal urea production (Fmo) were 0.49 and 0.37 mg/min per kg live weight respectively and there was a close correlation between the rate of maternal urea disposal (Fom) and the dietary nitrogen intake.4. The values of Ffo were used to calculate the maximum potential for foetal gluconeogenesis from deaminated amino acids. These calculations were compared with published information on the over-all rates of foetal gluconeo genesis in well-nourished ewes.5. The foetal entry rate of urea expressed on a body-weight basis was high, approximately 8.5 times that of the mother, but it was a threefold overestimate of Ffo. The maternal entry rate was 1.3 times Fmo and the significance of this in relation to assessing differences in urea entry rates in pregnant and non-pregnant sheep is discussed.

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