scholarly journals Precursors for ornithine and citrulline synthesis in neonatal pigs

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Juan C Marini ◽  
Barbara Stoll ◽  
Inka Cajo Didelija ◽  
Douglas G Burrin
Keyword(s):  
Neonatal Pigs ◽  
Citrulline Synthesis

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.

scholarly journals Adaptive changes in the capacity of systems used for the synthesis of citrulline in rat liver mitochondria in response to high- and low-protein diets

1974 ◽  
Vol 142 (2) ◽  
pp. 359-364 ◽  
Author(s):  
J. D. McGivan ◽  
Norah M. Bradford ◽  
J. B. Chappell
Keyword(s):  
Nitrogen Source ◽  
High Protein Diet ◽  
Liver Mitochondria ◽  
High Protein ◽  
Protein Diet ◽  
Rat Liver Mitochondria ◽  
Standard Diet ◽  
Adaptive Changes ◽  
Low Protein ◽  
Citrulline Synthesis

1. Citrulline synthesis was measured in mitochondria from rats fed on a standard diet, a high-protein diet, or on glucose. 2. With NH4Cl as the nitrogen source the rate of citrulline synthesis was higher in mitochondria from rats fed on a high-protein diet than in those from rats fed on a standard diet. When rats were fed solely on glucose the rate of synthesis of citrulline from NH4Cl was very low. 3. With glutamate as the nitrogen source the relative rates of citrulline synthesis were much lower than when NH4Cl was present, but similar adaptive changes occurred. 4. The activity of the mitochondrial glutamate-transporting system increased two to three times on feeding rats on a high-protein diet, but the Km for glutamate was unchanged. 5. Adaptive changes in certain intramitochondrial enzymes were also measured. 6. The results were interpreted to indicate that when an excess of substrate was present, citrulline synthesis from NH4Cl was rate-limited by the intramitochondrial concentration of N-acetyl-glutamate, but citrulline synthesis from glutamate was rate-limited primarily by the activity of the glutamate-transporting system.

scholarly journals Relationship between the Rate of Citrulline Synthesis and Bulk Changes in the Intramitochondrial ATP/ADP Ratio in Rat-Liver Mitochondria

1981 ◽  
Vol 113 (2) ◽  
pp. 295-302 ◽  
Author(s):  
Ron J. A. WANDERS ◽  
George M. WOERKOM ◽  
Ron F. NOOTEBOOM ◽  
Alfred J. MEIJER ◽  
Joseph M. TAGER
Keyword(s):  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Citrulline Synthesis

Effects of age and maternal reactivity on the stress response of the pituitary-adrenocortical axis and the sympathetic nervous system in neonatal pigs

1999 ◽  
Vol 68 (3) ◽  
pp. 519-526 ◽  
Author(s):  
E. Kanitz ◽  
W. Otten ◽  
G. Nürnberg ◽  
K. P. Brüssow
Keyword(s):  
Stress Reactivity ◽  
Acth Stimulation Test ◽  
Acth Stimulation ◽  
Acth Challenge ◽  
Neonatal Pigs ◽  
Age Related ◽  
Highly Sensitive ◽  
Function Test ◽  
Adrenal Response ◽  
Different Levels

AbstractThe study was conducted to investigate the adreno cortical capacity after injection of ACTH and the sensitivity of the pituitary and the adrenal to immobilization in neonatal pigs at different ages. Furthermore, the endocrine reactivity of the offspring was compared with the stress reactivity of their mothers. Four piglets were selected from each of six different litters and subjected to an immobilization test and an adrenal function test using synthetic ACTH1-24 at the ages of 7, 21 and 35 days; the six sows were also subjected to restraint and an ACTH stimulation test. Plasma β-endorphin, norepinephrine and epinephrine concentrations were measured in blood samples taken 2 min after restraint and cortisol concentrations were measured 60 min after ACTH administration. A highly sensitive adrenal response was demonstrated in both sows and piglets and adrenal reactivity showed also a considerable consistency over time within sows. In neonatal pigs, the cortisol response to ACTH was greatest on day 7 and decreased up to day 35. Plasma epinephrine and norepinephrine levels after the 2-min immobilization were also higher at day 7 compared with the other ages (P < 0·01). Piglets from sows, classified as high reacting according to their cortisol or epinephrine response, also showed significantly higher cortisol levels after ACTH challenge at all ages and significantly higher epinephrine levels after restraint at day 7 than piglets from low reacting sows. The results show an age-related change of pituitary-adrenocortical and sympatho-adrenomedullary responses in neonatal pigs and an absence of a stress hyporesponsive period at all ages studied. The results also indicate different levels of excitability in the offspring depending on the maternal stress reactivity.

scholarly journals Energetics of citrulline synthesis by rat liver mitochondria.

1981 ◽  
Vol 256 (14) ◽  
pp. 7287-7297
Author(s):  
J.R. Williamson ◽  
R. Steinman ◽  
K. Coll ◽  
T.L. Rich
Keyword(s):  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Citrulline Synthesis

scholarly journals Glutamine metabolism in chick enterocytes: absence of pyrroline-5-carboxylase synthase and citrulline synthesis

1995 ◽  
Vol 306 (3) ◽  
pp. 717-721 ◽  
Author(s):  
G Wu ◽  
N E Flynn ◽  
W Yan ◽  
D G Barstow
Keyword(s):  
Glutamine Metabolism ◽  
Nutritional Requirement ◽  
Ornithine Carbamoyltransferase ◽  
No Formation ◽  
Weaning Pig ◽  
Citrulline Synthesis ◽  
Metabolic Basis ◽  
Endogenous Synthesis ◽  
Positive Controls ◽  
In Cells

This study was designed to determine whether pyrroline-5-carboxylate (P-5-C) synthase is deficient in chick enterocytes therefore resulting in the lack of synthesis of ornithine and citrulline from glutamine. Post-weaning pig enterocytes, which are known to contain P-5-C synthase and to synthesize both ornithine and citrulline from glutamine, were used as positive controls. Enterocytes were incubated at 37 degrees C for 0-30 min in the presence of 2 mM [U-14C]glutamine or 2 mM ornithine plus 2 mM NH4Cl. In chick enterocytes, glutamine was metabolized to NH3, CO2, glutamate, alanine and aspartate, but not to ornithine, citrulline, arginine or proline. Likewise, there was no formation of citrulline, arginine, alanine or aspartate from ornithine in chick enterocytes. Furthermore, the rate of conversion of ornithine into proline in chick enterocytes was only about 4% of that in cells from pigs. To elucidate the reason for the inability of chick enterocytes to synthesize ornithine and citrulline from glutamine, the activities of the enzymes involved were measured. No activity of P-5-C synthase or ornithine carbamoyltransferase was found in chick enterocytes, in contrast with cells from post-weaning pigs. It was also demonstrated that the activity of ornithine aminotransferase in chick enterocytes was only 3% of that in cells from pigs. Thus the present findings elucidate the biochemical reason for the lack of endogenous synthesis of ornithine and citrulline in chicks. Our results also explain previous observations that ornithine cannot replace arginine or proline in the diet of chicks. We suggest that the absence of P-5-C synthase and ornithine carbamoyltransferase in enterocytes is the metabolic basis for the nutritional requirement of arginine in the chick.

KV7.1 channel blockade inhibits neonatal renal autoregulation triggered by a step decrease in arterial pressure

2022 ◽  
Author(s):  
Dieniffer Peixoto-Neves ◽  
Praghalathan Kanthakumar ◽  
Jeremiah M Afolabi ◽  
Hitesh Soni ◽  
Randal K Buddington ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Functional Expression ◽  
Renal Autoregulation ◽  
Neonatal Pigs ◽  
Vascular Smcs ◽  
Neonatal Pig ◽  
Kidney Maturation ◽  
Renal Vascular ◽  
Renal Vascular Tone ◽  
Fetal Pig

KV7, the voltage-gated potassium channels encoded by KCNQ genes, mediate heterogeneous vascular responses in adult rodents. Postnatal changes in the functional expression of KV7 channels have been reported in rodent saphenous arteries, but their physiological function in the neonatal renal vascular bed is unclear. Here, we report that, unlike adult pigs, only KCNQ1 (KV7.1) out of the five members of KCNQ genes was detected in neonatal pig renal microvessels. KCNQ1 is present in fetal pig kidneys as early as day 50 of gestation, and the level of expression remains the same up to postnatal day 21. Activation of the renal vascular smooth muscle cell (SMC) KV7.1 stimulated whole-cell currents, inhibited by HMR1556 (HMR), a selective KV7.1 blocker. HMR did not change the steady-state diameter of isolated renal microvessels. Similarly, intrarenal artery infusion of HMR did not alter the mean arterial pressure (MAP), renal blood flow (RBF), and renal vascular resistance (RVR) in the pigs. An approximately 20 mmHg reduction in the MAP evoked effective autoregulation of the RBF, which HMR inhibited. We conclude that 1) The expression of KCNQ isoforms in porcine renal microvessels is dependent on kidney maturation, 2) KV7.1 is functionally expressed in neonatal pig renal vascular SMCs, 3) a decrease in arterial pressure up to 20 mmHg induces renal autoregulation in neonatal pigs, and 4) SMC KV7.1 does not control basal renal vascular tone but contributes to neonatal renal autoregulation triggered by a step decrease in arterial pressure.

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