Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:021133 (ATP)
 132,114 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The crucial point in the pathogenesis of isoproterenol-induced myocardial necrotization is an abundant intracellular Ca accumulation leading to high energy phosphate exhaustion. Accordingly, in the early stage of the isoproterenol-induced necrotization process, the onset of ATP and creatine phosphate breakdown strictly parallels the acute Ca gain. In this type of necrosis, the Mg losses from the myocardium appear as a concomitant phenomenon. The hearts can be protected against the deleterious Ca overload and necrotization by increasing the plasma concentration of Mg, K, or H ions in order to counterbalance Ca according to the ration (see article). On the other hand, if Mg, K, or H ion concentrations are too low, isoproterenol-induced Ca uptake and myocardial lesions are potentiated.
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PMID:Prevention of myocardial Ca overload and necrotization by Mg and K salts or acidosis. 0 Jul 43

The value of the adenylate energy charge, i.e. ([ATP] + 1/2[ADP])/([ATP] + [ADP] + [AMP]), during batch culture of Beneckea natriegens remained relatively constant during the exponential and early stationary phases of the growth cycle. During exponential growth the intracellular ATP content remained constant, the amount of ATP in the culture increasing proportionally with growth; these conditions were unaltered during growth in the presence of added cyclic AMP. On cessation of growth, significant variation in bacterial ATP content was observed depending on whether growth of the cultures terminated due to exhaustion of carbon or nitrogen from the medium, and on the presence or absence of added cyclic AMP.
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PMID:Adenylate energy charge during batch culture of Beneckea natriegens. 1 48

The intracellular ATP content of Lactobacillus casei ATCC 27092 grown in a glucose-containing medium was almost constant (2 to 3 microgram/mg dry wt. cells) through the early to middle stage of logarithmic phase, but it was lowered to less than 0.1 microgram/mg after cessation of growth owing to the exhaustion of available glucose. All the cells in the early stage of stationary phase were still viable and thus considered to be in a starved state. When such starved cells were infected with PL-1 phages in a tris-maleate buffer of pH 6.0, the process of forming blender-resistant phage-cell complexes signifying the complete injection of phage genomes into the cells was much inhibited. There was a good correlation between the ATP content of cells and the extent of the formation of blender-resistant phage-cell complexes and the correlation coefficient between them was 0.89 + 0.09 at the 95% confidence limit. On the other hand, the process of forming both the phage-adsorbed cells and the anti-phage serum-resistant phage-cell complexes were not affected by the ATP content of cells. Feeding of glucose to such starved cell cultures caused the cells to restore both the ATP content and the ability to form blender-resistant phage-cell complexes. Such restoration was also observed when the starved cells collected by centrifugation were incubated in a glucose-containing medium. The significance of the intracellular level of high energy compounds such as ATP for the mechanism of the injection of phage genomes into the cells is discussed.
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PMID:Adenosine triphosphate content in Lactobacillus casei and the blender-resistant phage-cell complex-forming ability of cells on infection with PL-1 phage. 10

Experiments were carried out on male Wistar rats in order to clarify the leading biochemical mechanism responsible for an increase in the functional capacity of the heart. The obtained results indicate that the function of the Na,K-pump in myocardial sarcolemma is rather stable and deteriorates only during extreme exertion. The alteration of the Na,K-pump function due to a decrease in Na,K-ATP-ase activity leads to a decrease in the Na gradient and an accumulation of water in the cells which in turn reduces the capacity of the Na-Ca exchange mechanism and the rate of Ca removal from the myofibrils. Hence, the decrease in the working capacity of the heart during excessive physical exercises is primarily connected with the exhaustion of the ions active transport mechanism rather than the mechanism of aerobic energy production. In accordance with this conclusion, the functional stability of the myocardial Na,K-pump increased in our experiments with regular training, whereas the capacity to regenerate ATP via oxidative phosphorylation did not change, as demonstrated by Holloszy et al. Experiments in adrenalectomized animals, with or without administration of gluco- and mineralocorticoids, has revealed that an adequate supply of glucocorticoids to the heart is important in maintaining the function of the myocardial Na,K-pump and thereby in the working capacity of the heart during severe physical exertion.
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PMID:[Function of the sodium-potassium pump and its corticosteroid regulation as factors limiting cardiac adaptation to severe physical exertion]. 13 13

1. Questions concerning coronary heart disease have been raised for more than 200 years, but the concept of coronary insufficiency is only 50 years old. 2. The pathological anatomy of coronary insufficiency is variable, unexpectedly rich and stratified, and full of pecularities. 3. "Coronary insufficiency" is the superimposed concept; "cardiac infarcts" and "inner myocardial layer damage" are subordinate. 4. The logical connection linking all the morphological consequences of so-called coronary insufficiency is the elective necrosis of the parenchyma. The anatomically demonstrable equivalents of coronary insufficiency are, from the point of view of coronary perfusion, the result of an inadequate "vis a tergo". 5. This principle is enshrined in a complex of conditions which has to be disentangled if an individual case is to be analysed. The complex comprises three sets of factors: (a) the critical narrowing of the lumen of the coronary arteries and all their branches leading to a given territory; (b) the weight of the functioning mass of the cardiac muscle; (c) cardiac effort required of the heart during the critical period of damage. 6. The presence of anastomoses between the coronary arteries is no proof of their functional efficiency or readiness in an emergency. The conditions which determine their responsiveness, particularly as far as time is concerned, are at the moment still not adequately known. 7. The behaviour of ions at the membranes of living cells, particularly of muscle fibres, is a fundamental phenomenon, fascinating in its primitive aspects. A disturbance of cellular respiration, produced in the cardiac muscle "regularly" by the "inadequate vis a tergo" of coronary perfusion, leads to an exhaustion of energy stores, and to an increased influx of calcium ions. This activates the ATP-ase of the myofibrils, and thereby reduces the level of adenin nucleotides. This loss of energy-rich substances not only militates against the function of the muscle fibres, it also initiates their necrosis. 8. The cardiac infarct is a phenomenon of a disturbed circulation-- a "dyscirculatory" change. It is found in certain sites of predilection, whose choice becomes intelligible only through an understanding of the developmental history of the coronary arteries. The cardiac infarct is "coronary-dependent"! There are, however, also other forms of, and possibilities leading to, the development of myocardial necrosis. The nosology of the cardiac infarct clearly distinguishes the latter from these other forms. In damage of the inner layers of the myocardium infarcts do not develop by the confluence of necroses of individual fibres or of groups of fibres. Infarcts are not a phenomenon of addition, they do not have the "character of a mosaic". 9. As in other tissues, in the human myocardium also there are lysosomes. They are found in hypertrophied muscle fibres. Topical relations to zones of necrosis have not been found. 10...
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PMID:The pathogenesis of cardiac infarction. A few comments on some unanswered questions. 14 May 3

1. Formycin triphosphate (FTP), a fluorescent analogue of ATP, is a substrate for (Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3), with properties similar to those of ATP. 2. FTP and formycin diphosphate (FDP) bind to the enzyme with high affinity and, on binding, the nucleotide fluorescence is enhanced 3-4-fold. It is therefore possible, with a stopped-flow fluorimeter, to measure the rates of binding and release of FTP and FDP under conditions in which turnover does not occur. 3. When the enzyme-FTP complex is exposed to conditions permitting turnover (Mg2+, Na+ +/- K+), changes in fluorescence occur which can be explained by supposing that they reflect the interconversion of states with or without bound nucleotides. A rapid fall in fluorescence, that we attribute to the rapid release of FDP from newly phosphorylated enzyme, is followed by a steady state in which low fluorescence suggests that little nucleotide is bound. Eventually, exhaustion of FTP allows rebinding of FDP to the enzyme, which is signalled by a rise in fluorescence. 4. The estimated rate of FDP release from newly formed phosphoenzyme is unaffected by the presence of K+ (0-2 mM) or the concentration of FTP (1-20 micron). 5. Experiments with [gamma-32P]FTP show that about 1 mol of 32P is incorporated per mol of enzyme. The rate of phosphorylation of the enzyme by [gamma-32P]FTP has been measured with a rapid-mixing-and-quenching apparatus. 6. Kinetic data from the fluorescence and phosphorylation experiments show that the behaviour of the enzyme, at least at the low nucleotide concentrations employed, is consistent with the Albers-Post model, and is difficult to reconcile with models in which K+ acts at or before the step in which FDP is released during turnover.
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PMID:Elementary steps of the (Na+ + K+)-ATPase mechanism, studied with formycin nucleotides. 21 Aug 11

1. In an attempt to study the intracellular location of ATP in skeletal muscle the distribution of substances which absorb light at 260 nm wave-length has been studied in isolated muscle fibres with the aid of a modified U.V.-microscope.2. U.V.-absorption in resting frog fibres was found to be higher in the I band than in the A band which confirms earlier findings. In stretched fibres (sarcomere length 2.9-3.6 mum) an absorbing substance could be seen to be concentrated in a pair of narrow lines, centred at the Z-line. The separation of the lines increased with increasing sarcomere length.3. Snake fibres, with sparse triads located at the A-I junction, displayed an absorption pattern very similar to that of frog fibres. It is concluded that it is unlikely that the absorbing substance is associated with the sarcotubular system.4. The absorption pattern of frog fibres remained unchanged during a tetanus. No clear changes could be detected after a period of stimulation, neither after single twitches nor after repeated tetani.5. In further attempts to cause exhaustion, metabolically poisoned fibres were stimulated repetitively until they went into rigor. The absorption pattern was essentially unchanged also when rigor tension started to develop.6. The characteristic absorption pattern was observed also in glycerol-extracted fibres. It was confirmed by spectrophotometry that glycerol-extraction led to the disappearance of a large amount of a substance with the spectral characteristics of ATP.7. The higher U.V.-absorption in the I band does not prove that the major part of the ATP in the fibre is concentrated here; the absorption could either be due to a minor fraction of the ATP or to RNA.
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PMID:Location of U.V.-absorbing substance in isolated skeletal muscle fibres. The effect of stimulation. 30 60

In conditions of declining water PO2, Xenopus obtains the majority of resting oxygen needs from lung breathing at 15 degrees and 25 degrees C. The critical oxygen tension was 120 +/- 9 mm Hg at 15 degrees C, and 90 +/- 10 mm Hg at 25 degrees C. During 30 min stimulation of activity to complete exhaustion at 15 degrees C, frogs exhibited an aerobic capacity of 1.7 microliter O2.g-1.h-1 and accumulated 2.22 mg lactate . g-1. Following activity these animals exhibited an oxygen debt of 49.2 microliter O2.g-1. At 25 degrees C, Xenopus had an aerobic capacity of 16.1 microliter O2.g-1 and accumulated 1.94 mg lactate . g-1. Following activity, 25 degrees C frogs exhibited an oxygen debt of 261.9 microliter O2.g-1. Thus at 15 degrees C, Xenopus acquires 85% of the ATP used during a bout of sustained exhaustive activity from anaerobic sources, and 98% at 25 degrees C. Recovery from exhaustive activity was complete after 5 h at 25 degrees C and 9 h at 15 degrees C. Comparison of these data with those of other amphibians stimulated to sustained activity suggests that aquatic amphibians can tolerate a larger lactate load than can terrestrial forms.
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PMID:Aerobic and anaerobic contributions to sustained activity in Xenopus laevis. 51 65

The exposure of rats to 1 month continuous low-frequency vibration did not cause any changes in the brain adenylic fund and led to significant decrease in ATP content and total adenine nucleotides in the muscles of the extremities. For 3 months after the vibration there was a significant exhaustion of the brain and muscle adenylic fund. Under exposure to the interrupted vibration the state of adenine nucleotide system depended upon the duration of intervals limiting the continuous vibration effects. Under the vibration with the shortest intervals between each of the 30-minutes exposure there were no changes in the muscle and brain energy metabolism. 8- and 15-minute intervals for muscle adenine nucleotide and 8-minute interval for the brain proved to be unfavourable.
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PMID:[Changes in energy metabolism in the tissues of animals subjected to the effects of constant and intermittent low frequency vibration]. 67 48

1. Seven healthy male volunteers performed intermittent exercise (15 sec work--15 sec rest) at a high work load for 60 min and six subjects performed continuous exercise at an equally high load to exhaustion, which occurred after 4--6 min. 2. Muscle biopsies were obtained from the lateral portion of the quadriceps muscle before intermittent exercise and after the end of a work period and the end of the subsequent rest period at 5, 15, 30 and 60 min of exercise, as well as before, immediately after and about 15, 30, 60 and 180 sec after continuous exercise. 3. The reduction in glycogen content was smaller and glucose-6-phosphate, glycerol-1-phosphate, lactate and malate contents were lower after both work and rest periods in intermittent compared with continuous exercise, indicating a lower rate of glycolysis. 4. ATP and CP levels had decreased at the end of work periods in intermittent exercise but increased to slightly below basal in the subsequent rest periods. A still larger decrease in ATP and CP levels was found after continuous exercise to exhaustion and a progressive increase occurred over the 3 min of recovery. 5. In each rest period during intermittent exercise citrate levels increased to reach above basal. They increased also in the recovery phase after continuous exercise, although more slowly. 6. The findings support the assumption that ATP, CP and citrate act as regulatory factors of glycolysis in human muscle by retarding certain rate limiting steps. The increase in G-6-P/F-1-6-P2 ratio in rest periods of intermittent intense exercise and in the recovery phase of continuous intense exercise suggests that glycolysis is retarded at the phosphofructokinase reaction. 7. The factors mentioned may therefore contribute to the relative increase in lipid utilization during intense intermittent compared to continuous exercise.
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PMID:Regulation of glycolysis in intermittent exercise in man. 70 3


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