scholarly journals Glucose metabolism and its regulation in pieces of perirenal adipose tissue from foetal lambs

1983 ◽  
Vol 210 (3) ◽  
pp. 677-683 ◽  
Author(s):  
J P Robertson ◽  
A Faulkner ◽  
R G Vernon
Keyword(s):  
Adipose Tissue ◽  
Glucose Metabolism ◽  
Pyruvate Dehydrogenase ◽  
Glucose Utilization ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Near Term ◽  
Glucose 6 Phosphate Dehydrogenase

1. The following were measured in pieces of perirenal adipose tissue obtained from foetal lambs at about 120 days of gestation or within 3 days of term, and 9-month-old sheep: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO2 and the proportions contributed by the pentose phosphate cycle, pyruvate dehydrogenase and the tricarboxylic acid cycle; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase and pyruvate dehydrogenase. 2. The total rate of glucose utilization was lower in pieces of adipose tissue from near-term lambs than 120-day foetal lambs and the pattern of glucose metabolism differed, with, for example, a much smaller proportion of glucose carbon being used for fatty acid synthesis, whereas a greater proportion of glucose oxidation occurred via the tricarboxylic acid cycle in the near-term lambs. In general, these differences in glucose metabolism were not associated with differences in the activities of the various enzymes listed above. 3. The rates of glucose utilization per fat-cell by 120-day foetal lambs and 9-month-old sheep were very similar but, again, the proportions metabolized to the various products differed. In particular, there was a smaller proportion of glucose oxidized via the pentose phosphate cycle and a greater proportion oxidized via pyruvate dehydrogenase and the tricarboxylic acid cycle in adipose tissue from foetal lambs. These differences were matched by a lower activity of glucose 6-phosphate dehydrogenase and a higher pyruvate dehydrogenase activity in fat-cells from the foetal lambs.

The Pathway of Glucose Catabolism in Sporocytophaga myxococcoides

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 27-35 ◽  
Author(s):  
A. O. Hanstveit ◽  
J. Goksøyr
Keyword(s):  
Enzyme Activity ◽  
Acetic Acid ◽  
Glucose Metabolism ◽  
Pyruvic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Catabolic Pathways ◽  
Acid Cycle ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Pentose Pathway

The pathway of glucose metabolism in Sporocytophaga myxococcoides was studied by a radiorespirometric technique and assays of enzyme activity in cell-free extracts. The primary catabolic pathways in the organism were examined by measurement of relative rates of 14CO2-production from different carbon atoms of labelled glucose, pyruvic acid and acetic acid. These substrates appeared to be degraded solely by enzymes of the Embden-Meyerhof-Parnas pathway in conjunction with the tricarboxylic acid cycle. The results were confirmed by studies of enzyme activity, which showed a lack of two enzymes, glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate dehydrogenase, EC. 1.1.1.49) and 6-phospho-gluconate dehydrogenase [6-phospho-D-gluconate: NADP oxidoreductase (decarboxylating), EC. 1.1.1.44], in the pentose pathway, which indicated a biosynthetic function of the non-oxidative part of this pathway.

scholarly journals Biochemical adaptation in rat liver in response to marginal oxygen toxicity

1971 ◽  
Vol 125 (2) ◽  
pp. 439-447 ◽  
Author(s):  
R. R. Gorman ◽  
J. P. Jordan ◽  
J. B. Simmons ◽  
D. P. Clarkson
Keyword(s):  
Sea Level ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Oxygen Toxicity ◽  
Liver Glycogen ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Biochemical Adaptation ◽  
Glucose 6 Phosphate Dehydrogenase

1. Hepatic glucose 6-phosphate dehydrogenase activity was increased in rats exposed to 5lb/in2 (equivalent to 27000ft), 100% O2 when compared with control animals in a 14.7lb/in2 (sea level), air environment. Glyceraldehyde 3-phosphate dehydrogenase, isocitrate dehydrogenase, and succinate dehydrogenase were not affected by the 5lb/in2, 100% O2 environment. 2. Animals exposed to the hyperoxic environment consumed food, expired CO2 and gained weight at the same rate as normoxic control animals. Additionally, blood glucose and liver glycogen concentrations were unchanged in the hyperoxic animals. The only readily apparent physiological difference in the hyperoxic animals was a decreased haematocrit. 3. The increase in glucose 6-phosphate dehydrogenase was eliminated by the injection of actinomycin D or cycloheximide. 4. Expiration of 14CO2 from [1-14C]glucose was approximately the same in hyperoxic and normoxic rats. However, 14CO2 expiration from [6-14C]glucose was markedly decreased in the animals exposed to the hyperoxic environment. 5. Calculations of the relative importance of the pentose phosphate pathway versus the tricarboxylic acid cycle plus glycolysis indicated that the livers from animals in the 5lb/in2, 100% O2 environment metabolized twice as much carbohydrate by way of the pentose phosphate pathway as did those from the sea-level air control animals. 6. In livers of rats exposed to 5lb/in2, 100% O2 the concentrations of pyruvate, citrate and 2-oxoglutarate were increased, that of isocitrate was slightly elevated, whereas the concentrations of succinate, fumarate and malate were decreased. 7. An inactivation of both tricarboxylic acid cycle lipoate-containing dehydrogenases, pyruvate and 2-oxoglutarate, under hyperoxic conditions is proposed. 8. The adaptive significance of the induction of glucose 6-phosphate dehydrogenase and the resultant production of NADPH under hyperoxic conditions is discussed.

scholarly journals Metabolic phases during the development of granulation tissue

1967 ◽  
Vol 105 (1) ◽  
pp. 333-341 ◽  
Author(s):  
Kirsti Lampiaho ◽  
E. Kulonen
Keyword(s):  
Granulation Tissue ◽  
Collagen Synthesis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Short Period ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Observation Period

1. The metabolism of incubated slices of sponge-induced granulation tissue, harvested 4–90 days after the implantation, was studied with special reference to the capacity of collagen synthesis and to the energy metabolism. Data are also given on the nucleic acid contents during the observation period. Three metabolic phases were evident. 2. The viability of the slices for the synthesis of collagen was studied in various conditions. Freezing and homogenization destroyed the capacity of the tissue to incorporate proline into collagen. 3. Consumption of oxygen reached the maximum at 30–40 days. There was evidence that the pentose phosphate cycle was important, especially during the phases of the proliferation and the involution. The formation of lactic acid was maximal at about 20 days. 4. The capacity to incorporate proline into collagen hydroxyproline in vitro was limited to a relatively short period at 10–30 days. 5. The synthesis of collagen was dependent on the supply of oxygen and glucose, which latter could be replaced in the incubation medium by other monosaccharides but not by the metabolites of glucose or tricarboxylic acid-cycle intermediates.

scholarly journals Fibre-type specific modification of the activity and regulation of skeletal muscle pyruvate dehydrogenase kinase (PDK) by prolonged starvation and refeeding is associated with targeted regulation of PDK isoenzyme 4 expression

2000 ◽  
Vol 346 (3) ◽  
pp. 651-657 ◽  
Author(s):  
Mary C. SUGDEN ◽  
Alexandra KRAUS ◽  
Robert A. HARRIS ◽  
Mark J. HOLNESS
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Pyruvate Dehydrogenase ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pyruvate Dehydrogenase Kinase ◽  
Acid Cycle ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Anterior Tibialis

Using immunoblot analysis with antibodies raised against recombinant pyruvate dehydrogenase kinase (PDK) isoenzymes PDK2 and PDK4, we demonstrate selective changes in PDK isoenzyme expression in slow-twitch versus fast-twitch skeletal muscle types in response to prolonged (48 h) starvation and refeeding after starvation. Starvation increased PDK activity in both slow-twitch (soleus) and fast-twitch (anterior tibialis) skeletal muscle and was associated with loss of sensitivity of PDK to inhibition by pyruvate, with a greater effect in anterior tibialis. Starvation significantly increased PDK4 protein expression in both soleus and anterior tibialis, with a greater response in anterior tibialis. Starvation did not effect PDK2 protein expression in soleus, but modestly increased PDK2 expression in anterior tibialis. Refeeding for 4 h partially reversed the effect of 48-h starvation on PDK activity and PDK4 expression in both soleus and anterior tibialis, but the response was more marked in soleus than in anterior tibialis. Pyruvate sensitivity of PDK activity was also partially restored by refeeding, again with the greater response in soleus. It is concluded that targeted regulation of PDK4 isoenzyme expression in skeletal muscle in response to starvation and refeeding underlies the modulation of the regulatory characteristics of PDK in vivo. We propose that switching from a pyruvate-sensitive to a pyruvate-insensitive PDK isoenzyme in starvation (a) maintains a sufficiently high pyruvate concentration to ensure that the glucose → alanine → glucose cycle is not impaired, and (b) may ‘spare’ pyruvate for anaplerotic entry into the tricarboxylic acid cycle to support the entry of acetyl-CoA derived from fatty acid (FA) oxidation into the tricarboxylic acid cycle. We further speculate that FA oxidation by skeletal muscle is both forced and facilitated by upregulation of PDK4, which is perceived as an essential component of the operation of the glucose-FA cycle in starvation.

Carbohydrate metabolism in Acanthamoeba castellanii. 1. The activity of key enzymes and [14C]-glucose metabolism

1973 ◽  
Vol 19 (9) ◽  
pp. 1131-1136 ◽  
Author(s):  
Lansing M. Prescott ◽  
Harold E. Hoyme ◽  
Darlene Crockett ◽  
Elena Hui
Keyword(s):  
Carbohydrate Metabolism ◽  
Citrate Synthase ◽  
Tricarboxylic Acid Cycle ◽  
Fumarate Hydratase ◽  
Acanthamoeba Castellanii ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Key Enzymes ◽  
Glyceraldehydephosphate Dehydrogenase

The specific activities of a number of the key enzymes involved in carbohydrate metabolism in Acanthamoeba castellanii (Neff clone I–12) have been determined. The following Embden–Meyerhof and pentose phosphate pathway enzymes were present: glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphofructokinase, hexose diphosphatase, aldolase, glyceraldehydephosphate dehydrogenase, pyruvate kinase, and pyruvate-phosphate dikinase. The following tricarboxylic acid cycle enzymes were also found: citrate synthase, aconitase, isocitrate dehydrogenase, succinate dehydrogenase, fumarate hydratase, and malate dehydrogenase. The degradation of glucose-U-14C to 14CO2 was examined. Aerobic 14CO2 production from glucose-U-14C was 3.4-fold greater than anaerobic production. The data provide further evidence that the Embden–Meyerhof, pentose phosphate, and tricarboxylic acid cycle pathways are probably functional in A. castellanii.

Modulation of glucose metabolism in macrophages by products of nitric oxide synthase

1993 ◽  
Vol 264 (6) ◽  
pp. C1594-C1599 ◽  
Author(s):  
J. E. Albina ◽  
B. Mastrofrancesco
Keyword(s):  
Nitric Oxide ◽  
Glucose Metabolism ◽  
Oxidative Metabolism ◽  
Culture Media ◽  
Tricarboxylic Acid Cycle ◽  
Specific Inhibitor ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
The Impact ◽  
By Products

Nitric oxide (NO) is a product of L-arginine metabolism that suppresses cellular oxidative metabolism through the inhibition of tricarboxylic acid cycle and electron transport chain enzymes. The impact of NO synthase (NOS) activity on specific pathways of glucose metabolism in freshly harvested and overnight-cultured rat resident peritoneal macrophages, at rest and after stimulation with zymosan, was investigated using radiolabeled glucose. NOS activity was modulated through the L-arginine concentration in culture media and the use of its specific inhibitor, NG-monomethyl-L-arginine, and quantitated using radiolabeled L-arginine. Results demonstrated that NOS activity was associated with increased glucose disappearance, glycolysis, and hexose monophosphate shunt activity and, in line with the known inhibition of oxidative metabolism associated with the production of NO, with a decrease in the flux of glucose and butyrate carbon through the tricarboxylic acid cycle. In addition, the relative increase in glucose utilization that follows zymosan stimulation was enhanced by treatments that suppressed NOS activity. These results demonstrate that the characteristics of glucose metabolism by macrophages are, to a significant extent, determined by products of NOS.

Upregulation of Pentose Phosphate Pathway and Preservation of Tricarboxylic Acid Cycle Flux after Experimental Brain Injury

2005 ◽  
Vol 22 (10) ◽  
pp. 1052-1065 ◽  
Author(s):  
Brenda L. Bartnik ◽  
Richard L. Sutton ◽  
Masamichi Fukushima ◽  
Neil G. Harris ◽  
David A. Hovda ◽  
...  
Keyword(s):  
Brain Injury ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle

scholarly journals Metabolic changes in the lymphocytes during influenza

2012 ◽  
Vol 93 (4) ◽  
pp. 580-584
Author(s):  
I V Sergeeva ◽  
N I Kamzalakova ◽  
E P Tikhonova ◽  
G V Bulygin
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Tricarboxylic Acid Cycle ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Tricarboxylic Acid ◽  
Nicotinamide Adenine ◽  
Control Group ◽  
Healthy Individuals ◽  
Acid Cycle ◽  
Intracellular Enzymes ◽  
Glucose 6 Phosphate Dehydrogenase

Aim. To assess the nature and intensity of metabolic processes in lymphocytes of patients with influenza according to the activity of intracellular enzymes in comparison to the severity of the disease. Methods. Determined were the enzymatic parameters of lymphocytes of 45 patients aged 18 to 42 years with a diagnosis of «influenza». Two groups of patients were formed: with moderate (24 patients) and severe (21 patients) course of the disease. Used as controls were the values the activity of intracellular enzymes of lymphocytes of 37 practically healthy individuals of comparable age. Results. In patients with a moderately severe course of the influenza compared with the controls noted was a significant increase in activity of glucose-6-phosphate dehydrogenase (3.17±0.53 and 2.74±0.31 mkE/10 000 cells, p 0.05) and glycerol-3-phosphate dehydrogenase (57.33±±5.65 and 0.84±0.16 mkE/10 000 cells respectively, p 0.001). The activity of lactate dehydrogenase was lower in patients than in controls (0.40±0.08 and 0.84±0.08 mkE/10 000 cells respectively, p 0.001). Indicators of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate dependant isocitrate dehydrogenases in lymphocytes of patients were lower than in the controls: the first indicator in the patients was 0.17±0.02 mkE/10 000 cells, in controls - 1.95±0.25 mkE/10 000 cells (p 0.001), and for the second indicator these values were respectively 0.09±0.01 and 31.02±±2.20 mkE/10 000 cells (p 0.001). In patients with a moderately severe course of influenza the activity of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate dependant glutamate dehydrogenases was significantly higher compared with healthy individuals: 63.67±5.32 and 0.34±0.06 mkE/10 000 cells, 1.45±0.18 and 0.11±0.02 mkE/10 000 cells respectively (p 0.001). The activity of nicotinamide adenine dinucleotide dependant malate dehydrogenase in patients was equal to 86.46±12.30 mkE/10 000 cells (in the control group 84.16±13.70 mkE/10 000 cells), and the activity of nicotinamide adenine dinucleotide phosphate dependant malate dehydrogenase was equal to 1.34±±0.25 mkE/10 000 cells (in the control group 0.33±0.07 mkE/10 000 cells, p 0.001). The activity of glutathione reductase was also higher in patients with the moderately severe course of the influenza: 5.86±0.25 mkE/10 000 cells, while the value in healthy individuals was 1.28±0.30 mkE/10 000 cells (p 0.001). In the group of patients with a severe course of influenza the activity of almost all (except for glucose-6-phosphate dehydrogenase) enzymes was higher than during the moderately severe course of disease. Conclusion. At the peak of the diseases noted were opposite changes in the activity of reactions of the pentose phosphate cycle and glycolysis. With a high functional load on the cells there is a significant reduction in the intensity of the reactions of the initial phase of the tricarboxylic acid cycle, which reduces the energy efficiency of the cycle, while the intense influx of metabolites to supply the tricarboxylic acid cycle with substrates of the amino acid metabolism provides enhanced transport of amino acids into the lymphocytes.

Sign in / Sign up

Export Citation Format

Share Document