scholarly journals De novo synthesis is the main source of ornithine for citrulline production in neonatal pigs

2012 ◽  
Vol 303 (11) ◽  
pp. E1348-E1353 ◽  
Author(s):  
Juan C. Marini ◽  
Barbara Stoll ◽  
Inka Cajo Didelija ◽  
Douglas G. Burrin
Keyword(s):  
Amino Acid ◽  
De Novo ◽  
Neonatal Period ◽  
De Novo Synthesis ◽  
Physiological Factors ◽  
Neonatal Piglets ◽  
Neonatal Pigs ◽  
Citrulline Synthesis ◽  
Plasma Arginine ◽  
Infusion Protocol

Citrulline is an amino acid synthesized in the gut and utilized for the synthesis of the conditionally essential amino acid arginine. Recently, the origin of the ornithine utilized for citrulline synthesis has become a matter of discussion. Multiple physiological factors may have contributed to the differences found among different researchers; one of these is the developmental stage of the subjects studied. To test the hypothesis that during the neonatal period de novo synthesis is the main source of ornithine for citrulline synthesis, neonatal piglets were infused intravenously or intragastrically with [U-13C6]arginine, [U-13C5]glutamine, or [U-13C5]proline during the fasted and fed periods. [ ureido-15N]citrulline and [2H2]ornithine were infused intravenously for the entire infusion protocol. During fasting, plasma proline (13%) and ornithine (19%) were the main precursors for citrulline synthesis, whereas plasma arginine (62%) was the main precursor for plasma ornithine. During feeding, enteral (27%) and plasma (12%) proline were the main precursors for the ornithine utilized in the synthesis of citrulline, together with plasma ornithine (27%). Enteral proline and glutamine were utilized directly by the gut to produce ornithine utilized for citrulline synthesis. Arginine was not utilized by the gut, which is consistent with the lack of arginase activity in the neonate. Arginine, however, was the main source (47%) of plasma ornithine and in this way contributed to citrulline synthesis. In conclusion, during the neonatal period, the de novo pathway is the predominant source for the ornithine utilized in the synthesis of citrulline, and proline is the preferred precursor.

Proline ameliorates arginine deficiency during enteral but not parenteral feeding in neonatal piglets

1999 ◽  
Vol 277 (2) ◽  
pp. E223-E231 ◽  
Author(s):  
Janet A. Brunton ◽  
Robert F. P. Bertolo ◽  
Paul B. Pencharz ◽  
Ronald O. Ball
Keyword(s):  
Urea Cycle ◽  
De Novo ◽  
Parenteral Feeding ◽  
Central Vein ◽  
De Novo Synthesis ◽  
Neonatal Piglets ◽  
Vein Catheter ◽  
Central Vein Catheter ◽  
Arginine Deficiency ◽  
Plasma Arginine

The indispensability of arginine has not been conclusively established in newborns. Because parenteral feeding bypasses the gut (where de novo synthesis of arginine occurs from proline), a dietary supply of arginine that is sufficient to maintain urea cycle function may be of greater importance during intravenous compared with enteral feeding. Two-day-old piglets ( n = 12) were fed nutritionally complete diets for 5 days via either a central vein catheter (IV pigs, n = 6) or a gastric catheter (IG pigs, n = 6). Subsequently, each piglet received three incomplete test diets [arginine free (−ARG/+PRO), proline free (−PRO/+ARG), or arginine and proline free (−ARG/−PRO)] in a randomized crossover design. Plasma ammonia was assayed every 30 min for 8 h or until hyperammonemia was observed. Ammonia increased rapidly in IV pigs receiving −ARG/+PRO and −ARG/−PRO (84 ± 36 and 74 ± 37 μmol ⋅ l−1 ⋅ h−1, respectively), requiring early diet cessation. A rapid increase was also exhibited by IG pigs receiving the −ARG/−PRO, but not the −ARG/+PRO diet (31 ± 15 vs. 11 ± 7 μmol ⋅ l−1 ⋅ h−1, respectively, P < 0.05). Plasma arginine and proline were indicative of deficiency (IG and IV groups) when deplete diets were infused. Arginine is indispensable in parenteral and enteral nutrition, independent of dietary proline.

scholarly journals De Novo Synthesis of Amino Acids by the Ruminal Bacteria Prevotella bryantii B14,Selenomonas ruminantium HD4, and Streptococcus bovis ES1

1998 ◽  
Vol 64 (8) ◽  
pp. 2836-2843 ◽  
Author(s):  
Cengiz Atasoglu ◽  
Carmen Valdés ◽  
Nicola D. Walker ◽  
C. James Newbold ◽  
R. John Wallace
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
De Novo ◽  
Dependent Manner ◽  
Streptococcus Bovis ◽  
De Novo Synthesis ◽  
Ruminal Bacteria ◽  
Total N ◽  
Selenomonas Ruminantium ◽  
Prevotella Bryantii

ABSTRACT The influence of peptides and amino acids on ammonia assimilation and de novo synthesis of amino acids by three predominant noncellulolytic species of ruminal bacteria, Prevotella bryantii B14, Selenomonas ruminantiumHD4, and Streptococcus bovis ES1, was determined by growing these bacteria in media containing 15NH4Cl and various additions of pancreatic hydrolysates of casein (peptides) or amino acids. The proportion of cell N and amino acids formed de novo decreased as the concentration of peptides increased. At high concentrations of peptides (10 and 30 g/liter), the incorporation of ammonia accounted for less than 0.16 of bacterial amino acid N and less than 0.30 of total N. At 1 g/liter, which is more similar to peptide concentrations found in the rumen, 0.68, 0.87, and 0.46 of bacterial amino acid N and 0.83, 0.89, and 0.64 of total N were derived from ammonia by P. bryantii, S. ruminantium, andS. bovis, respectively. Concentration-dependent responses were also obtained with amino acids. No individual amino acid was exhausted in any incubation medium. For cultures of P. bryantii, peptides were incorporated and stimulated growth more effectively than amino acids, while cultures of the other species showed no preference for peptides or amino acids. Apparent growth yields increased by between 8 and 57%, depending on the species, when 1 g of peptides or amino acids per liter was added to the medium. Proline synthesis was greatly decreased when peptides or amino acids were added to the medium, while glutamate and aspartate were enriched to a greater extent than other amino acids under all conditions. Thus, the proportion of bacterial protein formed de novo in noncellulolytic ruminal bacteria varies according to species and the form and identity of the amino acid and in a concentration-dependent manner.

Transmembrane transport and intracellular kinetics of amino acids in human skeletal muscle

1995 ◽  
Vol 268 (1) ◽  
pp. E75-E84 ◽  
Author(s):  
G. Biolo ◽  
R. Y. Fleming ◽  
S. P. Maggi ◽  
R. R. Wolfe
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Human Skeletal Muscle ◽  
De Novo ◽  
Transmembrane Transport ◽  
Acid Transport ◽  
De Novo Synthesis ◽  
Intracellular Amino Acid

We have used stable isotopic tracers of amino acids to measure in vivo transmembrane transport of phenylalanine, leucine, lysine, alanine, and glutamine as well as the rates of intracellular amino acid appearance from proteolysis, de novo synthesis, and disappearance to protein synthesis in human skeletal muscle. Calculations were based on data obtained by the arteriovenous catheterization of the femoral vessels and muscle biopsy. We found that the fractional contribution of transport from the bloodstream to the total intracellular amino acid appearance depends on the individual amino acid, varying between 0.63 +/- 0.02 for phenylalanine and 0.22 +/- 0.02 for alanine. Rates of alanine and glutamine de novo synthesis were approximately eight and five times their rate of appearance from protein breakdown, respectively. The model-derived rate of protein synthesis was highly correlated with the same value calculated by means of the tracer incorporation technique. Furthermore, amino acid transport rates were in the range expected from literature values. Consequently, we conclude that our new model provides a valid means of quantifying the important aspects of protein synthesis, breakdown, and amino acid transport in human subjects.

Physiological hypercortisolemia increases proteolysis, glutamine, and alanine production

1988 ◽  
Vol 255 (3) ◽  
pp. E366-E373 ◽  
Author(s):  
D. Darmaun ◽  
D. E. Matthews ◽  
D. M. Bier
Keyword(s):  
Amino Acid ◽  
Plasma Cortisol ◽  
De Novo ◽  
Normal Subjects ◽  
Severe Trauma ◽  
Normal Diet ◽  
Whole Body ◽  
De Novo Synthesis ◽  
Body Protein ◽  
Cortisol Levels

Physiological elevations of plasma cortisol levels, as are encountered in stress and severe trauma, were produced in six normal subjects by infusing them with 140 micrograms.kg-1.h-1 of hydrocortisone for 64 h. Amino acid kinetics were measured in the postabsorptive state using three 4-h infusions of L-[1-13C]leucine, L-[phenyl-2H5]-phenylalanine, L-[2-15N]glutamine, and L-[1-13C]alanine tracers 1) before, 2) at 12 h, and 3) at 60 h of cortisol infusion. Before and throughout the study, the subjects ate a normal diet of adequate protein (0.8 g.kg-1.day-1) and energy intake. The cortisol infusion raised plasma cortisol levels significantly from 10 +/- 1 to 32 +/- 4 micrograms/dl, leucine flux from 83 +/- 3 to 97 +/- 3 mumol.kg-1.h-1, and phenylalanine flux from 34 +/- 1 to 39 +/- 1 (SE) mumol.kg-1.h-1 after 12 h of cortisol infusion. These increases were maintained until the cortisol infusion was terminated (64 h). These nearly identical 15% increases in two different essential amino acid appearance rates are reflective of increased whole body protein breakdown. Glutamine flux rose from 325 +/- 28 to 453 +/- 28 mumol.kg-1.h-1 by 12 h of cortisol infusion and remained elevated at the same level at 64 h. The increase in flux was primarily due to a 55% increase in glutamine de novo synthesis. Alanine flux increased from 207 +/- 13 to 285 +/- 23 mumol.kg-1.h-1 with acute hypercortisolemia and increased further to 475 +/- 59 mumol.kg-1.h-1 at 60 h of cortisol infusion, a result primarily of increased alanine de novo synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient increase of de novo amino acid synthesis and its physiological significance in water-stressed white clover

2005 ◽  
Vol 32 (9) ◽  
pp. 831 ◽  
Author(s):  
Bok-Rye Lee ◽  
Woo-Jin Jung ◽  
Kil-Yong Kim ◽  
Jean-Christophe Avice ◽  
Alain Ourry ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Water Deficit ◽  
White Clover ◽  
De Novo ◽  
Acid Synthesis ◽  
Ammonia Concentration ◽  
De Novo Synthesis ◽  
Amino Acid Synthesis ◽  
De Novo Protein Synthesis

In white clover (Trifolium repens L. cv. Regal) the kinetics of de novo synthesis of amino acid and protein were compared by tracing 15N under well-watered (control) or water-deficit conditions. The physiological relationship between ammonia concentration, in response to the change in leaf water parameters, and de novo synthesis of amino acid and protein was also assessed. Leaf and root dry mass were not significantly affected for the first 3 d, whereas metabolic parameters such as total N and ammonia were significantly affected within the first day of water-deficit treatment. Inhibitory effect of water deficit on N acquisition from the soil was significant throughout the experimental period. Water deficit induced a significant increase in ammonia concentration in leaves during the first 3 d, and in roots for only the first day. In both leaves and roots, an increase in de novo amino acid synthesis, which peaked in leaves within the first 3 d of water-deficit treatment (Ψw ≥ –1.18 MPa), was observed. The rate of decrease in de novo protein synthesis gradually accelerated as the duration of the water-deficit treatment increased. There was a significant positive relationship between ammonia production and the increase in de novo amino acid synthesis during the first 3-d period, but not during the later period (day 3–day 7). This experiment clearly indicates that the increase in de novo amino acid synthesis caused by water deficit is a transient adaptive response occurring during the first few days and that it is associated with the increased ammonia concentrations, which in turn arise in response to a decrease in de novo protein synthesis.

scholarly journals Arginine and ornithine kinetics in severely burned patients: increased rate of arginine disposal

2001 ◽  
Vol 280 (3) ◽  
pp. E509-E517 ◽  
Author(s):  
Yong-Ming Yu ◽  
Colleen M. Ryan ◽  
Leticia Castillo ◽  
Xiao-Ming Lu ◽  
Louis Beaumier ◽  
...  
Keyword(s):  
Amino Acid ◽  
Parenteral Nutrition ◽  
Healthy Volunteers ◽  
Burn Injury ◽  
De Novo ◽  
Multiple Roles ◽  
Burn Patients ◽  
De Novo Synthesis ◽  
Protein Kinetics ◽  
Indispensable Amino Acid

Arginine serves multiple roles in the pathophysiological response to burn injury. Our previous studies in burn patients demonstrated a limited net rate of arginine de novo synthesis despite a significantly increased arginine turnover (flux), suggesting that this amino acid is a conditionally indispensable amino acid after major burns. This study used [15N2-guanidino-5,5-2H2]arginine and [5-13C]ornithine as tracers to assess the rate of arginine disposal via its conversion to and subsequent oxidation of ornithine; [5,5-2H2]proline and [5,5,5-2H3]leucine were also used to assess proline and protein kinetics. Nine severely burned patients were studied during a protein-free fast (“basal” or fast) and total parenteral nutrition (TPN) feedings. Compared with values from healthy volunteers, burn injury significantly increased 1) fluxes of arginine, ornithine, leucine, and proline; 2) arginine-to-ornithine conversion; 3) ornithine oxidation; and 4) arginine oxidation. TPN increased arginine-to-ornithine conversion and proportionally increased irreversible arginine oxidation. The elevated arginine oxidation, with limited net de novo synthesis from its immediate precursors, further implies that arginine is a conditionally indispensable amino acid in severely burned patients receiving TPN.

scholarly journals Microcirculatory Function during Endotoxemia—A Functional Citrulline-Arginine-NO Pathway and NOS3 Complex Is Essential to Maintain the Microcirculation

2021 ◽  
Vol 22 (21) ◽  
pp. 11940
Author(s):  
Karolina A. P. Wijnands ◽  
Dennis M. Meesters ◽  
Benjamin Vandendriessche ◽  
Jacob J. Briedé ◽  
Hans M. H. van Eijk ◽  
...  
Keyword(s):  
Amino Acid ◽  
High Performance ◽  
De Novo ◽  
Dark Field ◽  
No Production ◽  
Beneficial Effects ◽  
Microcirculatory Flow ◽  
Plasma Arginine ◽  
Microcirculatory Function

Competition for the amino acid arginine by endothelial nitric-oxide synthase (NOS3) and (pro-)inflammatory NO-synthase (NOS2) during endotoxemia appears essential in the derangement of the microcirculatory flow. This study investigated the role of NOS2 and NOS3 combined with/without citrulline supplementation on the NO-production and microcirculation during endotoxemia. Wildtype (C57BL6/N background; control; n = 36), Nos2-deficient, (n = 40), Nos3-deficient (n = 39) and Nos2/Nos3-deficient mice (n = 42) received a continuous intravenous LPS infusion alone (200 μg total, 18 h) or combined with L-citrulline (37.5 mg, last 6 h). The intestinal microcirculatory flow was measured by side-stream dark field (SDF)-imaging. The jejunal intracellular NO production was quantified by in vivo NO-spin trapping combined with electron spin-resonance (ESR) spectrometry. Amino-acid concentrations were measured by high-performance liquid chromatography (HPLC). LPS infusion decreased plasma arginine concentration in control and Nos3−/−compared to Nos2−/−mice. Jejunal NO production and the microcirculation were significantly decreased in control and Nos2−/−mice after LPS infusion. No beneficial effects of L-citrulline supplementation on microcirculatory flow were found in Nos3−/−or Nos2−/−/Nos3−/−mice. This study confirms that L-citrulline supplementation enhances de novo arginine synthesis and NO production in mice during endotoxemia with a functional NOS3-enzyme (control and Nos2−/−mice), as this beneficial effect was absent in Nos3−/−or Nos2−/−/Nos3−/−mice.

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