Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AMINO ACID METABOLISM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed1986

Muscle ammonia and amino acid metabolism during dynamic exercise in man.

The effect of dynamic exercise on muscle and blood ammonia (NH3) and amino acid contents has been investigated. Eight healthy men cycled at 50% and 97% of maximal oxygen uptake for 10 min and 5.2 min (to fatigue), respectively. Biopsies (quadriceps femoris muscle), arterial and femoral venous blood samples were obtained at rest and during exercise. Muscle NH3 at rest and after submaximal exercise was (means +/- SE) 0.5 +/- 0.1 mmol/kg dry muscle (d.m.) and increased to 4.1 +/- 0.5 mmol/kg d.m. at fatigue (P less than 0.001). The total adenine nucleotide (TAN) pool (TAN = ATP + ADP + AMP) did not change after submaximal exercise but decreased significantly at fatigue (P less than 0.001). The decrease in TAN was similar to the increase in NH3. Muscle lactate was 3 +/- 1 mmol/kg d.m. at rest and increased to 104 +/- 5 mmol/kg d.m. at fatigue. Whole blood and plasma NH3 did not change significantly during submaximal but both increased significantly during maximal exercise (P less than 0.001). During maximal exercise the leg released 7,120 mumol/min of lactate, whereas only 89 mumol/min of NH3 were released. NH3 accumulation in muscle could buffer only 3% of the hydrogen ions released from lactate, and NH3 release could account for only 1% of the net hydrogen ion transport out of the cell. Muscle glutamine was constant throughout the study, whereas glutamate decreased and alanine increased during exercise (P less than 0.001). No significant changes in either arterial whole blood glutamine or glutamate were observed. Arterial plasma glutamine and glutamate concentrations, however, increased and decreased (P less than 0.001), respectively, during exercise. It is concluded that (1) muscle and blood NH3 levels increase only during strenuous exercise and (2) NH3 accumulation is of minor importance for regulating acid-base balance in body fluids during exercise.

Adult↗
PubMed1983

Protein and amino acid metabolism in posterior hemicorpus of acutely uremic rats.

Protein synthesis and degradation and net uptake and release of amino acids and minerals were examined in the perfused hemicorpus of bilaterally nephrectomized and sham-operated control rats. Animals were studied 30 h after surgery. In comparison with controls, uremic rats had greater urea N appearance (net urea generation) and lower plasma and muscle concentrations of most amino acids. Muscle protein synthesis was not altered, but protein degradation was greater in uremic versus sham rats. There was greater net release of phenylalanine, tyrosine, alanine, total nonessential amino acids, total amino acids, potassium, and phosphorus from the perfused hemicorpus of uremic rats and greater release of citrulline from sham rats. ATP, creatine phosphate, cAMP, and activities of cathepsin B1, cathepsin D, and alkaline protease were not different in muscles of the uremic versus sham rats. Thus, in acutely uremic rats there is increased protein wasting in the hemicorpus due to enhanced protein degradation. The enhanced protein degradation does not appear to be due to increased muscle cathepsin B1, cathepsin D, or alkaline protease activities.

Adenosine Triphosphate↗
PubMed1993

Application of high performance liquid chromatography in study of sulphur amino acid metabolism in uremic patients.

High-performance liquid chromatography (HPLC) was used for the quantitation of the free amino acids in plasma and muscle samples from 34 patients with chronic renal failure; of these patients, 18 were treated by hemodialysis (HD) and 16 by continuous ambulatory peritoneal dialysis (CAPD). Depletion of taurine was observed in plasma and muscle of uremic patients, whereas methionine was normal. Cysteine sulphinic acid was present in plasma of all uremic patients. The results suggest that taurine depletion is due to decreased endogenous synthesis in uremic patients.

Aged↗
PubMed2006

Sulfur amino acid metabolism in pregnancy: the impact of methionine in the maternal diet.

Animal studies show that the balance of methionine relative to other amino acids in the maternal diet is critical, as fetal growth is not only retarded by diets that are deficient but also by those containing excess. Diets with an inappropriate balance of methionine can adversely affect both short-term reproductive function and the long-term physiology of the offspring. The catabolism of unused methionine increases the demand for glycine and may cause a deficiency. High levels of methionine may also perturb intracellular S-adenosyl methionine pools and have an effect on the methylation of DNA and proteins. Excess methionine in the diet may also indirectly influence fetal development through the production of homocysteine or by the perturbation of endocrine functions. The metabolic interactions among dietary methionine, folic acid, and choline mean that other diet components can also change the methionine requirement.

Amino Acids, Sulfur↗
PubMed1976

Effects of ketone bodies on amino acid metabolism in isolated rat diaphragm.

1. Diaphragms from 48h-starved rats were incubated in Krebs-Ringer bicarbonate medium at 37degreesC for 30min and then transferred into new medium and incubated for 1, 2 and 3 h. 2. The amount of free amino acids found at the end of each time of incubation was larger than the amount at the beginning of incubation, indicating that in this system proteolysis is prevailing. 3. The diaphragms was releasing mainly alanine and glutamine into the incubation medium. 4. Within the periods of incubation the release and metabolism of free amino acids was proceeding at a constant rate. 5. Addition of sodium DL-3-hydroxybutyrate decreased the tissue content of several amino acids, among which were tyrosine and phenylalanine, suggesting that proteolysis was decreased by ketone bodies. 6. In the presence of glucose (10mM) and branched-chain amino acids (0.5mM), sodium DL-3-hydroxybutyrate at concentrations of 4 or 6 mM resulted in 30% decrease in tissue alanine content and a 20% decline in alanine release. Release of taurine and glutamine was decreased by 19 and 16% respectively with 6 mM-sodium DL-3-hydroxybutyrate. Addition of sodium acetoacetate (1-3mM) also resulted in a 20-35% decrease in tissue content of alanine, glutamine and taurine and in a 15-24% decrease of alanine and glutamine release. Smaller decreases (less than 15%) in the release of glycine, threonine, proline, serine and aspartate were also observed in the presence of sodium DL-3-hydroxybutyrate or sodium acetoacetate. 7. Substitution of pyruvate (1.0mM) for glucose in the presence of acetoacetate restored alanine and glutamine production to control values. In the presence of acetoacetate, pyruvate also increased the tissue content of aspartate by 77% and decreased the tissue content of glutamate by 30%. 8. It is suggested that in diaphragms from starved rats, ketone bodies (a) in the absence of other substrates inhibit protein catabolism and (b) in the presence of glucose and branched-chain amino acids decrease alanine and glutamine production, by inhibiting glycolysis.

Acetoacetates↗