Studies in the respiratory and carbohydrate metabolism of plant tissues - X. The influence of oxygen at high pressures as a stimulant and inhibitor of certain pathways of respiration in carrots

1961 ◽  
Vol 154 (956) ◽  
pp. 289-308 ◽  
Keyword(s):  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
High Oxygen ◽  
Total Carbon ◽  
Inhibitory Effects ◽  
Acid Cycle ◽  
Concentration Changes ◽  
Oxygen Poisoning

In contrast with the behaviour of peas (Turner & Quartley 1956; Pritchard 1959, 1961) but like that of various tissues (Johannsen 1888; Cass 1947; Barker, Quartley & Turner 1960), the rate of CO 2 output of whole carrots was stimulated initially in oxygen at a pressure of 5 atm prior to the strong inhibition characteristic of oxygen poisoning. The inhibition was associated with an accumulation of citrate together with a decrease in the contents of α -ketoglutarate, succinate, malate and oxaloacetate; later pyruvate, alcohol and acetate also increased. As in the earlier work with potatoes, peas and apples (Barker & Mapson 1955; Turner & Quartley 1956; Barker et al . 1960), these changes in the acids were attributed in part to the production of an enzymic ‘block’ first in the tricarboxylic acid cycle between citrate and α -ketoglutarate and later in the oxidation of pyruvate. The earlier observations of the activity of the tricarboxylic acid cycle in carrot slices were thus confirmed (Pritchard 1959; ap Rees & Beevers 1960). The ‘total carbon traffic’, representing the sum of the observed CO 2 output in high oxygen and the calculated amounts of CO 2 that would be derived by oxidation of the accumulations of citrate, pyruvate, alcohol and acetate, increased initially in high oxygen to a rate which was about double that of the CO 2 output in air. Considered in relation to this increased carbon traffic in respiration, there was thus initially in high oxygen a large inhibition of the CO 2 output. Oxygen at high pressures thus produced simultaneous stimula­tory and inhibitory effects on certain phases of the respiratory process in carrots. Initially in high oxygen only a small part of the CO 2 output could be accounted for by the observed concentration changes: e. g. the accumulation of citrate; a part of the ‘unknown’ CO 2 output is provisionally attributed, without direct evidence, to operation of the pentose phosphate pathway, earlier shown to be active in carrot slices (Beevers & Gibbs 1954; ap Rees & Beevers 1960).

Studies in the respiratory and carbohydrate metabolism of plant tissues XIII. The influence of oxygen at high pressures in increasing and decreasing the respiration of potatoes at 15 °C

1963 ◽  
Vol 158 (971) ◽  
pp. 143-155 ◽  
Keyword(s):  
Carboxylic Acid ◽  
Carbohydrate Metabolism ◽  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Total Carbon ◽  
Plant Tissues ◽  
Sugar Phosphate ◽  
Oxygen Inhibition ◽  
Acid Cycle

The CO 2 output of potatoes held at 15 °C in oxygen at a pressure of either 2 or 3 atm was first decreased, then increased and finally again decreased. The increase of CO 2 output was much larger than in carrots (Barker 1961); in oxygen at a pressure of 2 atm the rate of CO 2 output of potatoes was increased 4.6 fold; taking into account the accumulation of citrate, the ‘total carbon traffic’ was increased 5.6 fold in oxygen. This increase was believed to occur mainly in a pathway which was not the tricarboxylic acid cycle. As in potatoes held at 1 °C in an atmosphere of oxygen (Barker & Mapson 1955), citrate accumulated and α -ketoglutarate decreased in potatoes, held at 15 °C in oxygen at pressures of 2 or 3 atm; these changes were accepted as demonstrating the occurrence of the tri­-carboxylic acid cycle. The final decrease of CO 2 output in oxygen appeared not to be related to the occurrence of ‘blocks’ either between citrate and α -ketoglutarate or of pyruvate or α -ketoglutarate oxidases; the inhibition might be due to a shortage of sugar phosphate substrates, caused possibly by oxygen inhibition of cytochrome- c reductase. The outburst of CO 2 , which occurred in potatoes first held in oxygen and then returned to air, could not be attributed solely to oxidation of accumulated citrate.

Studies in the respiratory and carbohydrate metabolism of plant tissues - IX. Experimental studies of the influence of oxygen at high pressures on the respiration of apples and of a 'block' in the tricarboxylic acid cycle induced by 'oxygen poisoning'

1960 ◽  
Vol 152 (946) ◽  
pp. 88-108 ◽  
Keyword(s):  
Carbohydrate Metabolism ◽  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Experimental Studies ◽  
Tricarboxylic Acid ◽  
Plant Tissues ◽  
Acid Cycle ◽  
Marked Inhibition ◽  
Oxygen Poisoning

In contrast with peas (Turner & Quartley 1956; Pritchard 1959) apples treated with oxygen at pressures of 2½ or 5 atm showed complex changes with time in the rate of CO 2 output. These changes appeared to be due to the opposed effects of inhibitory and stimulatory processes; the latter caused a large increase in the rate of respiration in oxygen as compared with that of samples held in air. Although then the observed rate of CO 2 output after several days in oxygen was, in general, only a little slower than the rate in air, taking into account the increased rate of respiration in oxygen, there was in fact a marked inhibition of a part or parts of the respiratory process. There was also an accumulation in oxygen of pyruvate, alcohol and citrate and a decrease in the contents of α -ketoglutarate and oxaloacetate, as compared with apples in air. As in the earlier work with potatoes and peas (Barker & Mapson 1955; Turner & Quartley 1956), these changes in the acids were attributed in part to the production of an enzymic ‘block’ in the tricarboxylic acid cycle between citrate and α -ketoglutarate. The indication in previous work (Allentoff, Phillips & Johnston 1954) that the tricarboxylic acid cycle may operate in apples was thus supported. The paper includes data on the influence of a return to air at a pressure of one atmosphere following subjection to oxygen at high pressures.

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.

Studies in the respiratory and carbohydrate metabolism of plant tissues. VII. Experimental studies with potato tubers of an inhibition of the respiration and of a ‘block’ in the tricarboxylic acid cycle induced by ‘oxygen poisoning’

1955 ◽  
Vol 143 (913) ◽  
pp. 523-549 ◽  
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Experimental Studies ◽  
General Term ◽  
Tricarboxylic Acid ◽  
Pure Oxygen ◽  
Prolonged Treatment ◽  
Potato Tubers ◽  
Acid Cycle ◽  
Oxidation Reduction ◽  
Oxygen Poisoning

Prolonged treatment of potato tubers at 1° C with an atmosphere of pure oxygen eventually induces a marked inhibition of the rate of CO 2 output; there is also an accumulation of pyruvate and of 'citrate’ and a decrease in the contents of α -ketoglutarate and of malate as compared with potatoes held in air. These changes in the acids appear to be in accord with the development during sojourn in pure oxygen of a ‘block’ in the tricarboxylic acid cycle between ‘citrate’ and α -ketoglutarate. The indications in previous work (Barron, Link, Klein & Michel 1950; Barker & Mapson 1953 b ) that the tricarboxylic acid cycle may operate in potato tubers under certain metabolic conditions are thus supported. The treatment with pure oxygen also results in a progressive shift to the more oxidized state in the ascorbic acid and glutathione oxidation-reduction systems; finally, the potato tissue develops a brown discoloration presumably due to polyphenolase action. The change in the balance of the two oxidation-reduction systems towards oxidation may be caused, in part, by a reduced rate of regeneration of coenzyme II because of the ‘block’ in the tricarboxylic acid cycle. The paper also contains the results of preliminary experiments on the reversibility of the above changes. The data add to the knowledge of the varied metabolic phenomena which have been observed in many different types of living tissue, both plant and animal, and which are conveniently classified under the general term ‘oxygen poisoning’ (Stadie, Riggs & Haugaard 1944).

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.

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.

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 Maximum activities of key enzymes of glycolysis, glutaminolysis, pentose phosphate pathway and tricarboxylic acid cycle in normal, neoplastic and suppressed cells

1990 ◽  
Vol 265 (2) ◽  
pp. 503-509 ◽  
Author(s):  
M Board ◽  
S Humm ◽  
E A Newsholme
Keyword(s):  
Pyruvate Kinase ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Neoplastic Cells ◽  
Acid Cycle ◽  
Key Enzymes ◽  
Metastatic Cells ◽  
Tumorigenic Cells

1. Maximal activities of some key enzymes of glycolysis, the pentose phosphate pathway, the tricarboxylic acid cycle and glutaminolysis were measured in homogenates from a variety of normal, neoplastic and suppressed cells. 2. The relative activities of hexokinase and 6-phosphofructokinase suggest that, particularly in neoplastic cells, in which the capacity for glucose transport is high, hexokinase could approach saturation in respect to intracellular glucose; consequently, hexokinase and phosphofructokinase could play an important role in the regulation of glycolytic flux in these cells. 3. The activity of pyruvate kinase is considerably higher in tumorigenic cells than in non-tumorigenic cells and higher in metastatic cells than in tumorigenic cells: for non-tumorigenic cells the activities range from 28.4 to 574, for tumorigenic cells from 899 to 1280, and for metastatic cells from 1590 to 1627 nmol/min per mg of protein. 4. The ratio of pyruvate kinase activity to 2 x phosphofructokinase activity is very high in neoplastic cells. The mean is 22.4 for neoplastic cells, whereas for muscle from 60 different animals it is only 3.8. 5. Both citrate synthase and isocitrate dehydrogenase activities are present in non-neoplastic and neoplastic cells, suggesting that the full complement of tricarboxylic-acid-cycle enzymes are present in these latter cells. 6. In neoplastic cells, the activity of glutaminase is similar to or greater than that of hexokinase, which suggests that glutamine may be as important as glucose for energy generation in these cells.

Changes in the oxidative metabolism during maturation of amphibian oocytes

Development ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 175-186
Author(s):  
Arnaldo H. Legname ◽  
Hortensia Salomón De Legname
Keyword(s):  
Oxidative Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Mature Oocyte ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Winter Period ◽  
Acid Cycle ◽  
Glycolytic Activity ◽  
Cytoplasmic Maturation ◽  
Respiratory Stimulation

Some aspects of oxidative metabolism during cytoplasmic maturation of the Bufo arenarum oocyte have been studied. During the autumn-winter period (immature oocyte), carbohydrates are degraded through the glycolytic pathway, followed by the classical tricarboxylic acid cycle. During the spring—summer period (mature oocyte), carbohydrates are mainly used through the pentose phosphate cycle, while the tricarboxylic acid cycle operates as the glutamicaspartic cycle. The oxidative phosphorylation of ADP does not seem to change during oocyte maturation. Although maturation does not alter the absolute values of ATP and citrate in the oocyte, it determines their different compartmentalization, which, through phosphofructokinase, in turn regulates the glycolytic activity of the oocyte. Oxygen uptake decreases by about 40 % during maturation, while simultaneously, a marked increment in respiratory stimulation by 2,4-dinitrophenol is observed.

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