Glutamate and glutamine metabolism in the ovine placenta

1983 ◽  
Vol 101 (2) ◽  
pp. 275-281 ◽  
Author(s):  
Jennifer M. Pell ◽  
Marjorie K. Jeacock ◽  
D. A. L. Shepherd
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Placental Transfer ◽  
Umbilical Vein ◽  
Maternal Blood ◽  
Glutamine Metabolism ◽  
Arterial Blood ◽  
Foetal Circulation ◽  
Glutamine Synthesis ◽  
Glutamyl Transferase

SUMMARYThe concentration of glutamate and of glutamine was measured in whole blood obtained from a maternal artery, a uterine vein, a foetal artery and an umbilical vein of chronically catherized ewes and foetuses from 100 to 140 days after conception. The activities of glutamate dehydrogenase, phosphate-dependent glutaminase, phosphateindependent glutaminase, glutamine synthetase, γ-glutamyl transferase and glutamine-oxo-acid aminotransferase were measured in placentomes obtained from ewes during a similar period of gestation.The concentrations of glutamate in blood from maternal vessels remained constant, whereas there was a significant decline (P < 0·001) in the concentration of glutamate in foetal blood. Glutamine concentrations declined significantly (P < 0·05) in maternal blood and in foetal arterial blood (P < 0·001), whereas the concentration of glutamine in umbilical venous blood remained constant.Mean arterio-venous differences for glutamate indicated that there was no net uptake from or release into maternal blood by the uterus. However, there was a significant (P < 0·02) uptake of glutamate by the placenta from the foetal circulation. Glutamine release from the placenta into the foetal circulation increased as the foetus matured.Significant activities of glutamate dehydrogenase, γ-glutamyl transferase, glutamine synthetase and phosphate-dependent glutaminase were found in the placenta but there was no significant relationship between the activities of these enzymes and the gestational age of the foetus. The enzyme profile indicated that the placenta has a substantial potential for net glutamine synthesis.It is concluded that, for a 140-day foetus, the release of glutamine from the placenta accounts for more than half of its nitrogen requirement. Direct placental transfer of glutamine from maternal blood accounts for only one-third of the glutamine released by the placenta into the foetal circulation of a 140-day foetus. Therefore, the remainder of the glutamine is synthesized in the placenta from glutamate. Only one-third of the glutamate required for this placental glutamine synthesis is from the glutamate released by the foetus. The remainder must be derived either from 2-oxoglutarate, as the result of aminotransferase or glutamate dehydrogenase activities, or from glutathione by the action of γ-glutamyl transferase.

scholarly journals Submitochondrial localization and function of enzymes of glutamine metabolism in avian liver.

1977 ◽  
Vol 73 (2) ◽  
pp. 300-310 ◽  
Author(s):  
J E Vorhaben ◽  
J W Campbell
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Liver Mitochondria ◽  
Glutamine Metabolism ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
The Matrix ◽  
Matrix Compartment ◽  
Matrix Fraction ◽  
And Function

Glutamine synthetase (EC 6.3.1.2) was localized within the matrix compartment of avian liver mitochondria. The submitochondrial localization of this enzyme was determined by the digitonin-Lubrol method of Schnaitman and Greenawalt (35). The matrix fraction contained over 74% of the glutamine synthetase activity and the major proportion of the matirx marker enzymes, malate dehydrogenase (71%), NADP-dependent isocitrate dehydrogenase (83%), and glutamate dehydrogenase (57%). The highest specific activities of these enzymes were also found in the matrix compartment. Oxidation of glutamine by avian liver mitochondria was substantially less than that of glutamate. Bromofuroate, an inhibitor of glutamate dehydrogenase, blocked oxidation of glutamate and of glutamine whereas aminoxyacetate, a transaminase inhibitor, had little or no effect with either substrate. These results indicate that glutamine metabolism is probably initiated by the conversion of glutamine to glutamate rather than to an alpha-keto acid. The localization of a glutaminase activity within avian liver mitochondria plus the absence of an active mitochondrial glutamine transaminase is consistent with the differential effects of the transaminase and glutamate dehydrogenase inhibitors. The high glutamine synthetase activity (40:1) suggests that mitochondrial catabolism of glutamine is minimal, freeing most of the glutamine synthesized for purine (uric acid) biosynthesis.

scholarly journals Effect of hyperbaric oxygenation on metabolism of glutamine in the liver

2014 ◽  
Vol 60 (3) ◽  
pp. 364-371 ◽  
Author(s):  
P.N. Savilov
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Hyperbaric Oxygenation ◽  
Inhibitory Effect ◽  
Glutamine Metabolism ◽  
Albino Rats ◽  
Functional Heterogeneity ◽  
Glutamine Concentration ◽  
Hyperoxic Exposure ◽  
Stimulation Of

The effect of three-day course of hyperbaric oxygenation (HBO; 3 atm, 50 min, 1 session per day) on glutamine metabolism in the liver has been investigated in 72 adult albino rats. The content of ammonia, glutamate, glutamine, activity of glutamine synthetase (GS), phosphate-dependent glutaminase (PDG), and glutamate dehydrogenase (GDH) were studied in left (LLL) and median (MLL) lobes of the liver. The course of HBO had an inhibitory effect on all the enzymes studied. Inhibitory effect of hyperoxia on GDH activity persisted up to day 11 after the course of HBO in both lobes of the liver, while decreased glutamate normalized in both lobes. Reduced glutamine concentration normalized to day 4, and the concentration of ammonia and remained elevated for 11 days after the end of hyperoxic exposure. Inhibitory effect of hyperoxia on GS activity in LLL and MLL disappeared on day 4 and day 11 day after the end of the HBO course. PDG activity reduced by HBO in both lobes normalized to the day 4 day after oxygenation; however, on day 11 it selectively decreased in LLL, where simultaneous stimulation of GS activity was also observed. The results demonstrate different sensitivity of liver GS, PDG and GDH of normal rats to the inhibitory effect of HBO. Different dynamics of GS and PDG activity in LLL and MLL of oxygenated rats suggests functional heterogeneity of the glutamine cycle in hepatocytes of liver lobes after HBO

Placental transfer of I131-insulin in the rhesus monkey

1961 ◽  
Vol 200 (3) ◽  
pp. 471-476 ◽  
Author(s):  
J. B. Josimovich ◽  
E. Knobil
Keyword(s):  
Placental Transfer ◽  
Degradation Products ◽  
Venous Blood ◽  
Maternal Blood ◽  
Maternal Plasma ◽  
Maternal Circulation ◽  
Fetal Circulation ◽  
Fetal Plasma ◽  
Arterial Blood ◽  
Venous Plasma

Pregnant rhesus monkeys were anesthetized, their uteri were exposed, and the interplacental vessels (fetal circulation) were cannulated without incision of the amnion. This procedure permitted simultaneous sampling of maternal blood, umbilical venous blood and umbilical arterial blood. I131-labeled insulin injected into the material circulation was detected in umbilical venous plasma, within 5 minutes after the injection, by the use of a chromatographic procedure which permits the separation of I131-insulin from other iodinated compounds. The concentration of I131-insulin in fetal plasma did not exceed 20% of that found concurrently in maternal plasma. A marked umbilical arterial-venous difference in I131-insulin concentration was consistently observed. The concentration of iodinated degradation products of I131-insulin was considerably higher in umbilical arterial plasma than in umbilical venous plasma, suggesting rapid degradation of the labeled hormone by the fetus. Conversely, the injection of I131-insulin into the fetal circulation was followed by the appearance of significant quantities of the labeled hormone in the maternal circulation. These experiments lead to the conclusion that insulin can cross the primate placenta.

Glutamine metabolism in rat skeletal muscle wounded with lambda-carrageenan

1987 ◽  
Vol 252 (1) ◽  
pp. E49-E56
Author(s):  
J. E. Albina ◽  
W. Henry ◽  
P. A. King ◽  
J. Shearer ◽  
B. Mastrofrancesco ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glutamine Synthetase ◽  
Inflammatory Infiltrate ◽  
Marked Decrease ◽  
Glutamine Metabolism ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Rat Skeletal Muscle ◽  
Glutamine Synthesis ◽  
Cellular Components

Wounding with lambda-carrageenan results in a marked decrease in the intracellular-free glutamine content of rat skeletal muscle. The potential mechanisms for this finding, including alterations in glutamine release, glutamine utilization, and glutamine synthesis, were investigated in rats under pentobarbital anesthesia. Wounding did not increase glutamine release from muscle during incubation or isolated hindlimb perfusion. Wounded muscle utilized more glutamine than nonwounded muscle, as measured both by the production of [14C]O2 and of -glutamate from labeled glutamine. Maximal glutamine synthetase activity was increased by wounding. The increase in glutamine synthetase activity in wounded muscle was prevented by adrenalectomy and restored by replacement doses of corticosterone in wounded adrenalectomized animals. The decrease in muscle free glutamine induced by wounding is therefore not mediated by an increase in the release of this amino acid, nor by a reduction in the tissue capacity for glutamine synthesis, but by an increase in glutamine utilization at the site of injury. This difference is apparently determined by the utilization of glutamine by the cellular components of the inflammatory infiltrate, which were shown to be capable of active glutaminolysis.

Glutamate and glutamine metabolism in tissues of developing lambs

1983 ◽  
Vol 101 (2) ◽  
pp. 265-273 ◽  
Author(s):  
Jennifer M. Pell ◽  
Julia Tooley ◽  
Marjorie K. Jeacock ◽  
D. A. L. Shepherd
Keyword(s):  
Skeletal Muscle ◽  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Gradual Increase ◽  
Kidney Cortex ◽  
Transferase Activity ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Glutamyl Transferase ◽  
Glutaminase Activity

SUMMARYThe activities of glutamine synthetase, phosphate-dependent glutaminase, phosphate-independent glutaminase, glutamate dehydrogenase, γ-glutamyl transferase and glutamine-oxo-acid aminotransferase were assayed in liver, kidney cortex, brain (cerebral hemispheres), spleen, skeletal muscle and ileum obtained from lambs of 100–260 days conceptual age. A curve was fitted to each set of data relating enzyme activity and conceptual age.In the ileum, glutaminase and γ-glutamyl transferase activities declined during development. Glutamine synthetase activity in the spleen increased markedly after birth, whereas glutamate dehydrogenase activity declined as rumen function was established. In the liver, glutamate dehydrogenase and glutamine synthetase activities were highest in suckling lambs and there was a gradual increase in hepatic γ-glutamyl transferase activity throughout the period studied. The activity of phosphate-dependent glutaminase was lowest in the kidney cortex of ruminating lambs but renal activities of glutamate dehydrogenase, phosphate-independent glutaminase, glutamine synthetase and γ-glutamyl transferase were highest in ruminating lambs. In skeletal muscle, a gradual increase in glutamine synthetase activity occurred after 180 days conceptual age, whereas there was no detectable glutaminase activity in ruminating lambs. In the brain, there was an increase in glutamate dehydrogenase, phosphatedependent glutaminase and glutamine synthetase activities during the foetal and early suckling periods, whereas γ-glutamyl transferase activity increased throughout the period studied.Glutamine-oxo-acid aminotransferase activity was not detected in any of the tissues studied. Phosphate-independent glutaminase activity was always less than 10% of phosphate-dependent glutaminase activity and therefore must have a minor role in the metabolism of glutamine in lambs.A consideration of the relative activities of the enzymes at different stages of development indicated that the ileum, spleen, liver, kidney cortex and brain have a substantial potential for glutamine utilization during foetal life. As a lamb matures after birth, there are changes in the metabolism of glutamate and glutamine which indicate that there is a greater potential for net glutamine synthesis in older lambs. This could be associated with the need for detoxification of ammonia in ruminating lambs.

scholarly journals Glutamine metabolism in the gastrointestinal tract of the rat assessed by the relative activities of glutaminase (EC 3.5.1.2) and glutamine synthetase (EC 6.3.1.2)

1998 ◽  
Vol 79 (4) ◽  
pp. 365-372 ◽  
Author(s):  
L. A. James ◽  
P. G. Lunn ◽  
M. Elia
Keyword(s):  
Small Intestine ◽  
Glutamine Synthetase ◽  
Complete Information ◽  
Total Activity ◽  
External Source ◽  
Glutamine Metabolism ◽  
Gi Tract ◽  
Glutamine Synthesis ◽  
Low Levels ◽  
Glutaminase Activity

The activities of the two key enzymes involved in glutamine metabolism, glutaminase (EC 3.5.1.2) and glutamine synthetase (EC 6.3.1.2), have been measured in the various tissues of the gastrointestinal (GI) tract of the rat, from the mouth to the rectum. Glutaminase activity was particularly high in the mucosa of the small intestine, where its activity accounted for more than 80% of the total activity of the GI tract. In contrast, the mouth and oesophagus had very low activities, accounting for less than 2% of the total. Glutamine synthetase was mainly confined to the lower part of the stomach, which accounted for almost 90% of the total activity of the GI tract. Activity in the small intestine was very low, accounting for less than 2% of the total, and similarly low levels were found in the mouth and oesophagus. The data provide the most complete information on the distribution of these enzymes in the GI tract of the rat and suggest: (a) that the mucosa of the small intestine has the highest capacity for glutamine breakdown but the lowest capacity for its synthesis, and so requires an external source of this amino acid; (b) that there is little potential for glutamine synthesis or breakdown in the mouth and oesophagus; and (c) that the lower stomach has a substantial capacity to synthesize glutamine, in contrast to the rest of the GI tract. The results of the investigation are relevant to sites of glutamine metabolism in therapeutic studies involving glutamine administration discussed with reference to reports of the effects of glutamine administration on GI tract injury.

scholarly journals Metabolic engineering of Escherichia coli for efficient production of L-alanyl-L-glutamine

2020 ◽  
Author(s):  
Jiangming Zhu ◽  
Wei Yang ◽  
Bohua Wang ◽  
Qun Liu ◽  
Xiaotong Zhong ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Glutamic Acid ◽  
Water Solubility ◽  
Glutamine Metabolism ◽  
Cell Factory ◽  
Efficient Production ◽  
Microbial Cell Factory ◽  
Good Thermal Stability ◽  
Glutamine Synthesis ◽  
Engineered Strain

Abstract Background: L-alanyl-L-glutamine (AQ) is a functional dipeptide with high water solubility, good thermal stability and high bioavailability. It is widely used in clinical treatment, post-operative rehabilitation, sports health care and other fields. AQ is mainly produced via chemical synthesis which is complicated, time-consuming, labor-intensive, and have a low yield accompanied with the generation of by-products. It is therefore highly desirable to develop an efficient biotechnological process for the industrial production of AQ.Results: A metabolically engineered E. coli strain for AQ production was developed by over-expressing L-amino acid α-ligase (BacD) from Bacillus subtilis, and inactivating the peptidases PepA, PepB, PepD, and PepN, as well as the dipeptide transport system Dpp. In order to use the more readily available substrate glutamic acid, a module for glutamine synthesis from glutamic acid was constructed by introducing glutamine synthetase (GlnA). Additionally, we knocked out glsA-glsB to block the first step in glutamine metabolism, and glnE-glnB involved in the ATP-dependent addition of AMP/UMP to a subunit of glutamine synthetase, which resulted in increased glutamine supply. Then the glutamine synthesis module was combined with the AQ synthesis module to develop the engineered strain that uses glutamic acid and alanine for AQ production. The expression of BacD and GlnA was further balanced to improve AQ production. Using the final engineered strain p15/AQ10 as a whole-cell biocatalyst, 71.7 mM AQ was produced with a productivity of 3.98 mM/h and conversion rate of 71.7 %.Conclusion: A metabolically engineered strain for AQ production was successfully developed via inactivation of peptidases, screening of BacD, introduction of glutamine synthesis module, and balancing the glutamine and AQ synthesis modules to improve the yield of AQ. This work provides a microbial cell factory for efficient production of AQ with industrial potential.

scholarly journals Foetomaternal relationships of serum bile acid pattern estimated by high-pressure liquid chromatography

1982 ◽  
Vol 204 (1) ◽  
pp. 141-145 ◽  
Author(s):  
S Itoh ◽  
S Onishi ◽  
K Isobe ◽  
M Manabe ◽  
K Inukai
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Bile Acid ◽  
Bile Acids ◽  
High Pressure Liquid Chromatography ◽  
Placental Transfer ◽  
Umbilical Vein ◽  
Maternal Blood ◽  
Serum Bile Acid ◽  
Umbilical Blood

The bile acid patterns in the maternal and umbilical vein and artery serum samples were analysed by a two-step chromatographic method involving group separation by piperidinohydroxypropyl-Sephadex LH-20 and high-pressure liquid chromatography using immobilized 3 alpha-hydroxy steroid dehydrogenase. Glycochenodeoxycholate predominates in the maternal blood and taurochenodeoxycholate in the umbilical blood. In cases where a free bile acid was detected in the maternal blood, the same bile acid was also demonstrated in the corresponding cord blood. The concentrations of taurocholate and taurochenodeoxycholate were found to be significantly higher in the umbilical artery than in the corresponding umbilical vein. Our data suggest that there is a bidirectional placental transfer of free bile acids and that there is a transfer of taurine-conjugated primary bile acids from the foetus to the mother.

Lessons From the E-Ferol Tragedy

PEDIATRICS ◽  
1986 ◽  
Vol 78 (3) ◽  
pp. 503-506
Author(s):  
William F. Balistreri ◽  
Michael K. Farrell ◽  
Kevin E. Bove
Keyword(s):  
Vitamin E ◽  
Placental Transfer ◽  
Serum Vitamin ◽  
Maternal Blood ◽  
Blood Levels ◽  
Antioxidant Vitamin ◽  
Low Birth Weight Infants ◽  
Term Infants ◽  
Naturally Occurring ◽  
Supplemental Vitamin

"Those who cannot remember the past are condemned to repeat it."—G. Sabtatana Several factors combined to suggest that supplemental vitamin E should be administered to low birth weight infants. The persistent concern and controversy, the latter confounded by a paucity of data, have been discussed in recent editorials.1,2 At birh, tissue stores of the naturally occurring lipidsoluble antioxidant vitamin E (α-tocopherol) are low. The amount of total tocopherol in the tissue of premature infants is approximately one half that of full-term infants. 3 Maternal vitamin E supplementation seems to have minimal effect on serum vitamin E levels in the newborn because there is poor placental transfer; maternal blood levels are higher than cord levels.1-3

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