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Results for “AMINO ACID METABOLISM”

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PubMedDate not supplied

[Amino acid metabolism in liver tissue during the consumption of qualitatively different proteins].

To evaluate changes in the liver ability to metabolize amino acids during intake of different proteins, the content of free amino acids was measured in the blood of the portal and liver veins of rats fed krill protein and casein. After 48 h of fasting the animals were given a suspension of krill protein and casein at a rate of 540 mg protein per 100 g bw. After 0.5, 1, 3 and 6 h the content of free amino acids was measured in the blood of the portal and liver veins by ion exchange chromatography with the use of an automatic amino acid analyzer. Administration of krill protein brought about a high enough (63%) absorption of amino acids by the liver during the 6-hour experiment. The degree of casein absorption was 31%. As compared to casein, intake of krill protein led to an earlier saturation of the body with amino acids having branched chains (P less than 0.05). The enzymatic systems of amino acid metabolism responded to the supply of the proteins under study in the same manner, however the rate of adaptation was different, amounting to 0.5 h for krill protein and to 3 h for casein. It is evident that the enzymatic systems involved in amino acid metabolism respond to the intake of krill protein to a larger extent than enzymes involved in metabolism of casein amino acids.

Amino Acids↗
PubMed1983

[Effect of long space flights on amino acid metabolism].

The amino acid composition of the plasma and serum of Salyut-6 crewmembers who performed flights of different duration was investigated. The parameter was found to vary depending on the flight time and use of different countermeasures. The 75- and 185-day cosmonauts who did not exercise in a full measure showed a decrease in the amino acid pool typical of emergency situations. The 96-, 140- and 175-day crewmembers who exercised as prescribed exhibited the lack of changes in the total content of amino acids and variations in the content of individual amino acids. The results of the study of the amino acid composition can be applied to the evaluation of inflight countermeasures, e.g. exercises, and to the development of rehabilitation measures postflight.

Amino Acids↗
PubMed1992

Does a single bout of exercise cause adaptation of amino acid metabolism in pigs?

Amino acid responses to exercise stress in well-trained racehorses and human athletes are well characterised, but the knowledge of amino acid metabolism during and after exercise in inactive animal species is limited. To study this, plasma amino acid concentrations were measured in previously unexercised pigs which performed two exercise tests on a treadmill with an interval of one week. In general, the changes in amino acids were more pronounced after the second than after the first exercise bout. Alanine, glutamine, phenylalanine and tyrosine were elevated for one hour only after the latter exercise. Twenty-four hours after the second exercise isoleucine, leucine, phenylalanine, tyrosine and valine were increased, but only isoleucine was increased after the first test. These differences between the two tests might be explained by adaptation of the amino acid metabolism after a single exercise bout and suggest that domestic pigs are well suited to study the early effects of exercise.

Adaptation, Physiological↗
PubMed1985

Metabolic effects of amino acid solutions in severely burned patients: with emphasis on sulfur amino acid metabolism and protein breakdown.

The metabolic effects of TPN containing high amounts of amino acids (18 gm N) was evaluated with respect to sulfur amino acid metabolism and protein breakdown in nine severely burned patients. The results were compared to corresponding data from burned patients receiving more moderate amounts of amino acids (9.2 gm N) or isocaloric amounts of carbohydrate and fat. Significantly increased urinary excretion and intracellular muscle tissue concentrations of methionine were found in patients receiving the concentrated amino acid solution, probably reflecting a combined effect of the injury and an increased load of the compound. These patients also showed a reduced oxidation of sulfur amino acids to inorganic sulfate, which may reflect an increased protein synthesis during treatment. A significantly decreased urinary excretion of 3-methyl-histidine and mercaptolactate was found in patients receiving the concentrated amino acid solution, probably reflecting a decreased breakdown of body protein. The findings favor the hypothesis of an anabolic effect of the new amino acid solution in burned patients during the early catabolic phase, but also emphasize the importance of monitoring the amounts of amino acids, e.g., methionine, given.

Adult↗
PubMed1992

[Amino acid metabolism in endogenous psychoses: significance of amino acids as neurotransmitter, precursor of monoamines and allosteric regulator of neuro-receptors].

Amino acid metabolism in endogenous psychoses has been discussed in relation to monoamine synthesis. There are no consistent findings which prove altered monoamine syntheses to be the primary change. Our finding, which suggests decreased amino acid transport across the blood-brain barrier in schizophrenia, does not necessarily mean an insufficient amino acid supply to the brain. Several lines of investigation have shown the possibility of the involvement of glutamatergic dysfunction in the pathogenesis of schizophrenia. Our recent finding of decreased CSF asparagine concentration in schizophrenia and its positive correlation with the response to neuroleptics may support this hypothesis. Recently, free D-serine, an allosteric agonist on NMDA-receptor, has been reported to exist in the rat brain, suggesting that D-serine is an intrinsic ligand. The pathogeneses of endogenous psychoses might be studied in terms of disturbed metabolism of amino acid, as allosteric regulater of neuro-receptor, as well as neurotransmitter and precursor of monoamines.

Amino Acids↗
PubMed2004

Animal models of amino acid metabolism: a focus on the intestine.

One important advantage of animal models is that they permit invasive approaches and can be especially valuable when evaluating tissue and specific features of metabolism in situ. The focus of this presentation is current models, which are providing insights into the pivotal importance of the gastrointestinal tract in amino acid metabolism. Intestinal amino acid metabolism is conceptually and technically difficult to approach and multiple processes must be accounted for: protein synthesis and degradation; transit of amino acids in both directions across the basolateral surface of enterocytes, in addition to uptake on the apical side; arterio-portal differences as well as net portal appearance during uptake of defined amino acid mixtures appearing on the luminal side; first pass amino acid metabolism. These key features are largely impossible to study without access to invasive approaches in vivo and cannot be reproduced in vitro. Douglas Burrin, Ron Ball, and Vickie Baracos and their co-workers have used the domestic piglet to study intestinal protein metabolism in situ in three distinctly different and complementary approaches. Collectively, their approaches allow a means to describe the key elements of intestinal amino acid capture (and release) and the means to probe their physiological and pathological variation. It seems evident that the portal-drained viscera represent sites of quantitatively important amino acid catabolism, and that this capacity combined with hepatic metabolism would largely limit the possibility of toxic sequelae of amino acids taken orally.

Amino Acids↗
PubMed1992

[Amino acid metabolism in surgical stress].

Amino acid metabolism under surgical stress, injury or infection was reviewed from the literature. The glucose-alanine cycle in coupling with branched chain amino acids (BCAA) metabolism plays a central role for gluconeogenesis, in such a catabolic state. Glutamine is as important as alanine for sparing glucose and furthermore for intestinal repair. Changes in plasma amino acid concentration and clearance following hepatectomy are described, and effects of BCAA solution are evaluated. It was suggested that BCAA improved the Fischer ratio by increasing, not only plasma BCAA level, but also AAA clearance.

Alanine↗