Effect of Dietary Protein and Amino Acid Mixture on Protein Synthesis <i>in vitro </i>in Rat Liver

Six normal untrained men were studied during the intravenous infusion of a balanced amino acid mixture (approximately 0.15 g.kg-1.h-1 for 3 h) at rest and after a leg resistance exercise routine to test the influence of exercise on the regulation of muscle protein kinetics by hyperaminoacidemia. Leg muscle protein kinetics and transport of selected amino acids (alanine, phenylalanine, leucine, and lysine) were isotopically determined using a model based on arteriovenous blood samples and muscle biopsy. The intravenous amino acid infusion resulted in comparable increases in arterial amino acid concentrations at rest and after exercise, whereas leg blood flow was 64 +/- 5% greater after exercise than at rest. During hyperaminoacidemia, the increases in amino acid transport above basal were 30-100% greater after exercise than at rest. Increases in muscle protein synthesis were also greater after exercise than at rest (291 +/- 42% vs. 141 +/- 45%). Muscle protein breakdown was not significantly affected by hyperminoacidemia either at rest or after exercise. We conclude that the stimulatory effect of exogenous amino acids on muscle protein synthesis is enhanced by prior exercise, perhaps in part because of enhanced blood flow. Our results imply that protein intake immediately after exercise may be more anabolic than when ingested at some later time.

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The effect of osmolarity on mouse parthenogenesis

Development ◽

10.1242/dev.31.2.513 ◽

1974 ◽

Vol 31 (2) ◽

pp. 513-526

Author(s):

M. H. Kaufman ◽

M. A. H. Surani

Keyword(s):

Protein Synthesis ◽

Culture Medium ◽

Culture Media ◽

Polar Body ◽

Amino Acid Mixture ◽

Culture Conditions ◽

Follicle Cells ◽

Acid Mixture ◽

Second Polar Body

Eggs from (C57B1 × A2G)F1 mice were activated by treatment with hyaluronidase, which removed the follicle cells, and cultured in vitro. Observations were made 6–8 h after hyaluronidase treatment to determine the frequency of activation and the types of parthenogenones induced. Cumulus-free eggs resulting from hyaluronidase treatment were incubated for 2¼ h in culture media of various osmolarities. The frequency of activation was found to be dependent on the postovulatory age of oocytes, while the types of parthenogenones induced were dependent on the osmolarity of the in vitro culture medium and their postovulatory age. Culture in low osmolar medium suppressed the extrusion of the second polar body (2PB). This decreased the incidence of haploid eggs with a single pronucleus and 2PB and immediately cleaved eggs from 97·5% to 42·3% of the activated population. Where 2PB extrusion had been suppressed, 97·4% of parthenogenones contained two haploid pronuclei. Very few were observed with a single and presumably diploid pronucleus. Serial observations from 11 to 18 h after hyaluronidase treatment were made on populations of activated eggs as they entered the first cleavage mitosis after 2¼ h incubation in medium either of normal (0·287 osmol) or low (0·168 osmol) osmolarity. A delay in the time of entry into the first cleavage mitosis similar to the duration of incubation in low osmolar medium was observed. Further, eggs were incubated in control and low osmolar culture media containing uniformly labelled [U-14C]amino acid mixture to examine the extent of protein synthesis in recently activated eggs subjected to these culture conditions. An hypothesis is presented to explain the effect of incubation in low osmolar culture medium in delaying the first cleavage mitosis.

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Biphasic increase in ornithine decarboxylase and its relationship with thymidine kinase and DNA synthesis in liver: Effects of dietary protein and amino acid mixture

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(80)91129-8 ◽

1980 ◽

Vol 93 (3) ◽

pp. 661-667 ◽

Cited By ~ 1

Author(s):

Ishtiaq Mahmud ◽

Mineko Asanagi ◽

Yoshiaki Miura

Keyword(s):

Amino Acid ◽

Dna Synthesis ◽

Thymidine Kinase ◽

Ornithine Decarboxylase ◽

Dietary Protein ◽

Amino Acid Mixture ◽

Acid Mixture

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Biotin-mediated protein biosynthesis

Biochemical Journal ◽

10.1042/bj1400549 ◽

1974 ◽

Vol 140 (3) ◽

pp. 549-556 ◽

Cited By ~ 24

Author(s):

R. L. Boeckx ◽

K. Dakshinamurti

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Rat Liver ◽

Intestinal Mucosa ◽

Protein Biosynthesis ◽

Amino Acid Incorporation ◽

Acid Incorporation ◽

Stimulation Of

The effect of administration of biotin to biotin-deficient rats on protein biosynthesis was studied. Biotin treatment resulted in stimulation by more than twofold of amino acid incorporation into protein, both in vivo and in vitro in rat liver, pancreas, intestinal mucosa and skin. Analysis of the products of amino acid incorporation into liver proteins in vivo and in vitro indicated that the synthesis of some proteins was stimulated more than twofold, but others were not stimulated at all. This indicates a specificity in the stimulation of protein synthesis mediated by biotin.

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Dietary amino acids: effect of depletion and recovery on synthesis in vitro in rat skeletal muscle and liver

British Journal Of Nutrition ◽

10.1079/bjn19740009 ◽

1974 ◽

Vol 31 (1) ◽

pp. 67-76 ◽

Cited By ~ 26

Author(s):

P. T. Omstedt ◽

Alexandra Von Der Decken

Keyword(s):

Skeletal Muscle ◽

Amino Acid ◽

Energy Levels ◽

Wheat Gluten ◽

Amino Acid Mixture ◽

Acid Mixture ◽

Amino Acid Mixtures ◽

Wet Weight ◽

Ribosomal Activity

1. Rats were given diets containing 200 g/kg of a complete or incomplete amino acid mixture or of high- or low-quality proteins. After 6 d the amino acid-incorporating activity of ribosomes from skeletal muscle and liver was studied.2. The level of isotope incorporation relative to ribosomal RNA was similar for casein supplemented with methionine and for a complete amino acid mixture with the composition of whole-egg protein. Per wet weight of tissue there was a significant decrease after feeding with the complete amino acid mixture.3. There was a significant decrease in activity after feeding with amino acid mixtures deficient in lysine, methionine or tryptophan. In skeletal muscle, but not in liver, the ribosomal activity was less than that obtained with wheat gluten. Activity per wet weight of both tissues was less than that obtained with wheat gluten.4. Refeeding with methionine for 1 d resulted in complete restoration of ribosomal activity and activity per wet weight in skeletal muscle.5. After lysine deficiency, protein synthesis per unit wet weight of both tissues and ribosomal activity in liver were not restored after 2 d of refeeding. Recovery of ribosomal activity in skeletal muscle was complete after 1 d.6. Rats receiving the 200 g casein/kg diet supplemented with methionine at daily energy levels of 263, 176, 141 and 106 KJ (62.6, 42.1, 33.7 and 25.3 kcal) showed no changes in ribosomal activity, but there was a significant decrease in activity per wet weight when 106 KJ were given.

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Carbohydrate formation from various precursors in neonatal rat liver

Biochemical Journal ◽

10.1042/bj1100725 ◽

1968 ◽

Vol 110 (4) ◽

pp. 725-731 ◽

Cited By ~ 13

Author(s):

R. G. Vernon ◽

Susan W. Eaton ◽

D G Walker

Keyword(s):

Amino Acid ◽

Rat Liver ◽

Neonatal Period ◽

Casein Hydrolysate ◽

Amino Acid Mixture ◽

Neonatal Rat ◽

Acid Mixture ◽

Hepatic Gluconeogenesis ◽

Threonine Dehydratase ◽

Serine Dehydratase

1. Measurements of the net synthesis of glucose plus glycogen from various precursors in slices of glycogen-depleted livers from rats at various stages of development indicated an increase in the gluconeogenic capacity after birth with l-lactate, oxaloacetate, a casein hydrolysate, l-serine, l-threonine, l-alanine and glycerol as substrates. 2. The highest rates of incorporation of 14C-labelled precursors into glucose plus glycogen in slices of normal livers of rats of various ages were observed in such tissue preparations from neonatal animals for an amino acid mixture, l-alanine, l-serine and l-threonine. 3. The activities of rat hepatic l-serine dehydratase and l-threonine dehydratase increase rapidly after birth and show maxima about 20 days later. 4. The results provide further evidence of the increased capacity for hepatic gluconeogenesis in the neonatal period and suggest various sites of regulation of the process.

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Endotoxemia reduces skeletal muscle protein synthesis in neonates

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00220.2002 ◽

2002 ◽

Vol 283 (5) ◽

pp. E909-E916 ◽

Cited By ~ 40

Author(s):

Renan A. Orellana ◽

Pamela M. J. O'Connor ◽

Hanh V. Nguyen ◽

Jill A. Bush ◽

Agus Suryawan ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Amino Acid ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Interleukin 1 ◽

Amino Acid Mixture ◽

Acid Mixture ◽

Skeletal Muscle Protein ◽

Skeletal Muscle Protein Synthesis

Protein synthesis in skeletal muscle is reduced by as much as 50% as early as 4 h after a septic challenge in adults. However, the effect of sepsis on muscle protein synthesis has not been determined in neonates, a highly anabolic population whose muscle protein synthesis rates are elevated and uniquely sensitive to insulin and amino acid stimulation. Neonatal piglets ( n = 10/group) were infused for 8 h with endotoxin [lipopolysaccharide (LPS), 0 and 10 μg · kg−1 · h−1]. Plasma amino acid and glucose concentrations were kept at the fed level by infusion of dextrose and a balanced amino acid mixture. Fractional protein synthesis rates were determined by use of a flooding dose of [3H]phenylalanine. LPS infusion produced a septic-like state, as indicated by an early and sustained elevation in body temperature, heart rate, and plasma tumor necrosis factor-α, interleukin-1, cortisol, and lactate concentrations. Plasma levels of insulin increased, whereas glucose and amino acids decreased, suggesting the absence of insulin resistance. LPS significantly reduced protein synthesis in longissimus dorsi muscle by only 11% and in gastrocnemius by only 15%, but it had no significant effect in masseter and cardiac muscles. LPS increased protein synthesis in the liver (22%), spleen (28%), kidney (53%), jejunum (19%), diaphragm (21%), lung (50%), and skin (13%), but not in the stomach, pancreas, or brain. These findings suggest that, when substrate supply is maintained, skeletal muscle protein synthesis in neonates compared with adults is relatively resistant to the catabolic effects of sepsis.

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