Excretion of Taurine during Healing of Experimental Wounds

1960 ◽  
Vol 6 (2) ◽  
pp. 140-147 ◽  
Author(s):  
Martin B Williamson ◽  
John M Passmann
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Total Nitrogen ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Nitrogen Excretion ◽  
Amino Acid Nitrogen ◽  
Protein Free Diet

Abstract A comparison of the excretion of amino acids by normal and wounded rats on a high protein and protein-free diet was made. The nontaurine amino acid nitrogen excretion was found to be the same the control and wounded animals, although the rats on the high protein diet excreted considerably more amino acid nitrogen than did those on the protein-free diet. The wounded animals on the high protein diet had the same total nitrogen output but excreted significantly larger amounts of taurine than did the nonwounded controls. The wounded animals given the protein-free diet excreted the same amount of taurine but produced more total nitrogen than did the control rats. On the basis of the total nitrogen-taurine excretion ratios, data indicate that cystine is conserved by the wounded as compared to the normal animals.

Fluxes and membrane transport of amino acids in rat liver under different protein diets

1990 ◽  
Vol 259 (5) ◽  
pp. E614-E625 ◽  
Author(s):  
P. Fafournoux ◽  
C. Remesy ◽  
C. Demigne
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acids ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Transport Systems ◽  
Low Concentrations ◽  
Significant Uptake

The aim of the present work was to evaluate in vivo the role of the transport step in hepatic amino acid metabolism. To vary hepatic utilization of amino acids, rats were adapted to diets containing various concentrations of casein (5, 15, and 60%). In rats fed 5 or 15% casein diets, Gln and Glu were released by the liver, and there was a significant uptake of Ala. Hepatic fluxes of amino acids increased considerably after adaptation to high-casein diet (up to 1.55 mumol.min-1.g liver-1 for Ala), because of the rise in afferent concentrations as well as enhanced uptake percentage (peaking at 60–75% for most glucogenic amino acids). Adaptation to a high-protein diet led to induction of not only system A but also of most of the other transport systems (Gly, anionic, T, y+, and to a lesser extent system N); only systems ASC and L were unchanged. The study of amino acid repartition between liver and plasma with different diets indicates that transport could modulate utilization of Ala, Ser, Thr, Gly, Gln, and Asp. For Arg and Asn, present in very low concentrations in liver under any condition, the transport step should be the major locus of control of their metabolism. For amino acids chiefly transported by nonconcentrative systems, such as aromatic amino acids, cellular metabolism could also be limited by the transport process. In conclusion, during adaptation to a high-protein diet, there is apparently a coordinated adaptation of amino acid transport and of their intracellular metabolism. For some amino acids, induction of catabolic enzymes seems greater than that of transport, so that the transport step may play an important role in control of metabolic fluxes. For example, concentration of amino acids such as Thr may be markedly depressed in rats adapted to a high-protein diet.

scholarly journals The nitrogen-sparing effect of methionine sulphoxide and some other sulphur-containing amino acids

1982 ◽  
Vol 48 (3) ◽  
pp. 565-570 ◽  
Author(s):  
L. R. Njaa ◽  
A. Aksnes
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
High Protein Diet ◽  
Negative Control ◽  
High Protein ◽  
Protein Diet ◽  
Short Term ◽  
Sparing Effect ◽  
Protein Free Diet

1. The nitrogen-sparing effect of methionine, methionine sulphoxide, homocystme, cystine and choline was studied in rats by determining daily N excretions during 5 d after changing from a high-protein diet to a protein-free diet, L-glutamic acid was used as a negative control.2. L-, D- and DL-methionine were equally active in sparing N. L-methionine sulphoxide, DL-homocystine and L-cystine were as active as L-methionine. D-methionine sulphoxide was slightly less active than L-methionine sulphoxide, Choline hydrogen tartrate was not different from the negative control.3. It is concluded that in short-term experiments cystine is the key substance in the N-sparing effect.

scholarly journals The role of phosphoenolpyruvate carboxykinase in amino acid metabolism in muscle

1978 ◽  
Vol 176 (2) ◽  
pp. 623-626 ◽  
Author(s):  
E A Newsholme ◽  
T Williams
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Malate Dehydrogenase ◽  
Amino Acid Metabolism ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Acid Metabolism ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet

Starvation or feeding rats on a high-protein diet, valine or isoleucine, but not leucine, increases the activity of muscle phosphoenolpyruvate carboxykinase, but has no effect on NADP+-linked malate dehydrogenase. This suggests that muscle phosphoenolpyruvate carboxykinase is involved in oxidation or conversion of some amino acids to alanine.

scholarly journals Performance of Broilers Fed Low Protein Diets with Lysine and Methionine Supplements

2006 ◽  
Vol 6 (1) ◽  
pp. 47-59
Author(s):  
Nancy Montilla ◽  
◽  
Lolito Bestil ◽  
Sulpecio Bantugan ◽  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Content ◽  
High Protein Diet ◽  
Protein Diet ◽  
Amino Acid Supplementation ◽  
Feed Conversion ◽  
Broiler Performance ◽  
Acid Supplementation ◽  
Low Protein

A feeding trial with broilers was conducted to evaluate the effects of amino acids (lysine and methionine) supplementation of diets low in protein content on the voluntary intake, feed conversion efficiency, broiler performance, and cost and return of broiler production. Results showed cumulative voluntary feed intake was not significantly affected by lowering the protein content of the diet. Cumulative weight gain of broilers was lower with diet when supplemented iwht lysine and methionine to meet requirements. Birds fed with diets low in protein has less efficient feed converstion, but became comparable with those receiveing diets high in protein when supplemented with amino acids. Feed cost per kilogram broiler produced was not significantly affected by diets used in the study, although the low-protien diet with amino acid supplement had the lowest values. In terms of return above feed and chick cost, broilers fed with high-protein diet had the greatest value, but not significantly different from birds fed with low-protien diet with amino acid supplementation which gave about P10 per bird higher returns than those fed low-protein diet without amino acid supplementation.

Metabolic Effects of the Use of Protein-Sparing Infusions in Postoperative Patients

1980 ◽  
Vol 58 (6) ◽  
pp. 507-515 ◽  
Author(s):  
K. J. Foster ◽  
K. G. M. M. Alberti ◽  
C. Binder ◽  
Leslie Hinks ◽  
S. Karran ◽  
...  
Keyword(s):  
Amino Acids ◽  
Blood Glucose ◽  
Amino Acid ◽  
Total Nitrogen ◽  
Insulin Infusion ◽  
Ketone Bodies ◽  
Treated Group ◽  
Saline Infusion ◽  
Nitrogen Excretion ◽  
Protein Sparing

1. The mechanism of the purported protein-sparing effects of different postoperative intravenous regimens still remains controversial. We have therefore measured circulating concentrations of metabolites and hormones in blood and urine nitrogen excretion in patients receiving (a) sodium chloride solution (saline), (b) 1.5 g of glucose day−1 kg−1 body weight, (c) 1.5 g of glucose day−1 kg−1 with insulin (0.56 unit day−1 kg−1) or (d) mixed amino acids (1.5 g day−1 kg−1) after abdominal operation. 2. Compared with results for saline-treated patients, glucose infusion resulted in raised glucose and insulin concentrations and lowered ketone body and non-esterified fatty acid concentrations but did not influence protein catabolism. 3. Addition of insulin lowered blood glucose by approximately 1 mmol/l. Total nitrogen excretion during glucose/insulin infusion was significantly less than during saline infusion. 4. Infusion of amino acids, compared with saline infusion, resulted in raised blood glucose, alanine, serum insulin and plasma glucagon concentrations but lower concentrations of plasma non-esterified fatty acids and blood ketone bodies. Insulin concentrations, however, were similar in both amino acid- and glucose-treated groups. 5. Amino acid infusion increased urea and total nitrogen excretion but net nitrogen loss was only 1.9 mmol of nitrogen day−1 kg−1 compared with 12.7 mmol day−1 kg−1 in the saline-treated group and 11.0 mmol day−1 kg−1 in the glucose-treated group. 6. Glucose (and insulin) infusion appeared to inhibit gluconeogenesis, and amino acids to enhance it. The nitrogen-sparing effect of amino acids appears largely related to their mass and is apparently unrelated to changes in ketone bodies and insulin.

scholarly journals Characterization of homocysteine metabolism in the rat liver

2000 ◽  
Vol 350 (3) ◽  
pp. 685-692 ◽  
Author(s):  
Lori M. STEAD ◽  
Margaret E. BROSNAN ◽  
John T. BROSNAN
Keyword(s):  
Amino Acid ◽  
Dietary Protein ◽  
High Protein Diet ◽  
Plasma Homocysteine ◽  
High Protein ◽  
Protein Diet ◽  
Total Plasma ◽  
Methionine Concentration ◽  
Protein Group

Recent evidence suggests that an increased plasma concentration of the sulphur amino acid homocysteine is a risk factor for the development of vascular disease. The tissue(s) responsible for homocysteine production and export to the plasma are not well known. However, given the central role of the liver in amino acid metabolism, we developed a rat primary hepatocyte model in which homocysteine (and cysteine) production and export were examined. The dependence of homocysteine export from incubated hepatocytes on methionine concentration fitted well to a rectangular hyperbola, with half-maximal homocysteine export achieved at methionine concentrations of approx. 0.44mM. Hepatocytes incubated with 1mM methionine and 1mM serine (a substrate for the transulphuration pathway of homocysteine removal) produced and exported significantly less homocysteine (25–40%) compared with cells incubated with 1mM methionine alone. The effects of dietary protein on homocysteine metabolism were also examined. Rats fed a 60% protein diet had a significantly increased total plasma homocysteine level compared with rats fed a 20% protein diet. Invitro effects of dietary protein were examined using hepatocytes isolated from animals maintained on these diets. When incubated with 1mM methionine, hepatocytes from rats fed the high protein diet exported significantly more homocysteine compared with hepatocytes from rats fed the normal protein diet. Inclusion of serine significantly lowered homocysteine export in the normal protein group, but the effect was more marked in the high protein group. Invivo effects of serine were also examined. Rats fed a high protein diet enriched with serine had significantly lower total plasma homocysteine (25–30%) compared with controls. These data indicate a significant role for the liver in the regulation of plasma homocysteine levels.

Splanchnic sequestration of amino acids in aged rats: in vivo and ex vivo experiments using a model of isolated perfused liver

2008 ◽  
Vol 294 (3) ◽  
pp. R748-R755 ◽  
Author(s):  
M. Jourdan ◽  
L. Cynober ◽  
C. Moinard ◽  
M. C. Blanc ◽  
N. Neveux ◽  
...  
Keyword(s):  
Amino Acids ◽  
Ex Vivo ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Aged Rats ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Urea Production

Splanchnic sequestration of amino acids (SSAA) is a process observed during aging that leads to decreased peripheral amino acid (AA) availability. The mechanisms underlying SSAA remain unknown. The aim of the present study was to determine whether a high-protein diet could increase nitrogen retention in aged rats by saturating SSAA and whether SSAA could be explained by dysregulation of hepatic nitrogen metabolism. Adult and aged male Sprague-Dawley rats were housed in individual metabolic cages and fed a normal-protein (17% protein) or high-protein diet (27%) for 2 wk. Nitrogen balance (NB) was calculated daily. On day 14, livers were isolated and perfused for 90 min to study AA and urea fluxes. NB was lower in aged rats fed a normal-protein diet than in adults, but a high-protein diet restored NB to adult levels. Isolated perfused livers from aged rats showed decreased urea production and arginine uptake, together with a release of alanine (vs. uptake in adult rats) and a hepatic accumulation of alanine. The in vivo data suggest that SSAA is a saturable process that responds to an increase in dietary protein content. The hepatic metabolism of AA in aged rats is greatly modified, and urea production decreases. This result refutes the hypothesis that SSAA is associated with an increase in AA disposal via urea production.

Sign in / Sign up

Export Citation Format

Share Document