Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.3.1 (citrate synthase)
4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of chronic administration for 6 weeks of an anabolic steroid, nandrolone phenylpropionate (Durabolin), was studied in three predominantly glycolytic muscles, and three oxidative muscles of sedentary female rats. Mean blood pressure and resting heart rate (HR) were lower in the anabolic-treated group, while the increase in HR during stimulation of EDL was reduced. No change was noted in the aerobic capacity of ventricular myocardium, although there was an increase in skeletal muscles due to a combination of increased capillary supply and/or TCA cycle enzyme activity. Capillary:fibre ratio (C:F) increased around 10% in glycolytic muscle with little effect on resting blood flow (BF). In EDL C:F was 1.1 +/- 0.02 vs. 1.2 +/- 0.01 and BF was 7.0 +/- 1.45 vs. 6.2 +/- 1.82 ml min-1 100 g-1 for control and Durabolin treated animals, respectively (means +/- SEM, n = 7). No increase in citrate synthase (CS) activity was evident. In soleus, where C:F was not significantly different between groups, CS activity increased from 3.9 +/- 0.34 to 5.9 +/- 0.40 microM g-1 min-1 (means +/- SEM, n = 7). Glycolytic capacity, indicated by pyruvate kinase activity, increased only in diaphragm. These data demonstrate that total oxidative metabolism of striated muscle does not necessarily increase with greater proportion of FOG fibres, nor is it always correlated with capillary supply. The positive myotrophic effect of Durabolin represents the sum of modest changes at different levels of organisation.
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PMID:Effects of an anabolic hormone on aerobic capacity of rat striated muscle. 343 43

Activities of eight enzymes were measured in the sonic muscle of the gulf toadfish, Opsanus beta, to determine the metabolic poise of this unique tissue and to evaluate potential sex related differences in metabolism. In contrast to a prior study (Pennypacker et al., '85, J. Exp. Zool., 239: 259-264), we observed substantial activities of M4-lactate dehydrogenase, 333 to 482 units/g wet sonic muscle weight. This observation and the presence of high activities of other enzymes of glycolytic and anaerobic metabolism (pyruvate kinase and creatine phosphokinase) lead us to conclude that this tissue has high anaerobic capacity. Also in contrast to the observations of Pennypacker et al. ('85), we found that the activities of some enzymes indicative of aerobic metabolism are relatively low. For example, the activities of citrate synthase found in sonic muscle (1.5 to 2.7 units/g) are only slightly higher than values obtained for toadfish white skeletal muscle (1.2 units/g). The discrepancies between the results obtained by the two studies appear to be methodological ones. Lastly, significant differences in enzyme activities between males and females were observed for lactate dehydrogenase, malate dehydrogenase, and citrate synthase, and possible explanations for these differences are discussed.
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PMID:Reexamination of metabolic potential in the toadfish sonic muscle. 355 99

The effects of isoprenaline administration (300 micrograms/kg for 5 weeks) on rat soleus muscle capillarity and glycolytic and oxidative capacities were evaluated. The treatment resulted in ventricular hypertrophy. The activities of lactic dehydrogenase, pyruvate kinase, citrate synthase, and cytochrome c oxidase in soleus muscle homogenates were not different between control and isoprenaline-injected animals. Capillaries were visualized in muscle cross sections treated to demonstrate ATPase activity after acid preincubation. Capillary density was higher in the experimental (873 +/- 38 capillaries/mm2) than in the control (713 +/- 33 capillaries/mm2) animals. Capillary to fiber ratio was also higher in the experimental (2.47 +/- 0.10) than in control (2.09 +/- 0.08) animals, but fiber cross-sectional area was not changed by the treatment (2836 +/- 87 microns2 in controls and 2951 +/- 136 microns2 in experimental). A plot of capillary to fiber ratio vs. fiber cross-sectional area showed that at a given fiber cross-sectional area the value of capillary to fiber ratio of the treated animals was higher than that of the controls. This indicates that treatment resulted in the proliferation of microvessels. The results suggest that prolonged beta-adrenergic stimulation results in the development of new capillaries but that this is not accompanied by increases in the oxidative capacity of the soleus muscle of the rat.
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PMID:Long-term isoprenaline administration produces an increase in capillarity in the soleus muscle of the rat. 358 Sep 52

Individual muscle fibers from patients with Duchenne muscular dystrophy at an early stage in their disease, and from apparently normal boys of similar age, were analyzed for 13 enzymes of energy metabolism. This approach avoided the serious problems with muscle homogenate assays from increases in nonparenchymal components and permitted assessment of disease changes in different fiber types. Some enzymes of glycogenolysis (phosphorylase, phosphoglucomutase, and pyruvate kinase) were decreased in dystrophic fibers of all types. Phosphofructokinase was decreased in presumptive type II fibers. Lactate dehydrogenase was increased in type I fibers and essentially unchanged in type II. Phosphoglucoisomerase was near normal. Two enzymes of glucose metabolism not involved in glycogenolysis, hexokinase and glycogen synthase, were near normal, but a third, fructose bisphosphatase, was sharply reduced. Two enzymes of oxidative metabolism, citrate synthase, and beta-hydroxyacyl CoA dehydrogenase, were unchanged or increased. Two enzymes of high energy phosphate transfer, creatine kinase and adenylokinase, were only marginally affected. The net result is to leave the type II fibers, which normally exert the greatest force, with a severe deficit in the glycogenolytic enzyme machinery to maintain that force.
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PMID:Effect of Duchenne muscular dystrophy on enzymes of energy metabolism in individual muscle fibers. 360 Feb 88

The activities of several enzymes of glucose metabolism (glycolytic and tricarboxylic acid pathways) in four different regions of rat brain (cerebellum, medulla oblongata and pons, cerebral cortex and diencephalon) have been studied. Statistical differences were found in the activities of all the enzymes analyzed in the four regions, except in the case of the soluble hexokinase and pyruvate kinase. The changes observed in citrate synthase activity may account for physiological differences in those areas related to myelin formation and energy metabolism. Cerebral cortex and diencephalon showed enzyme activities which were generally greater than those of the cerebellum and medulla oblongata and pons. The results obtained lend support to the concept of a differential energy metabolism in brain regions.
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PMID:Differences in the distribution of energy-metabolizing enzymes in rat brain regions. 361 4

In three groups of healthy young subjects (n = 33; mean ages 6.4, 13.5, 17.1 years), muscle enzyme activities (creatine kinase, hexose phosphate isomerase, aldolase, pyruvate kinase, lactate dehydrogenase, citrate synthase, fumarase) of the vastus lateralis muscle were investigated to show age-dependent variations. A significant age-dependent increase in aldolase (P less than 0.05) and pyruvate kinase (P less than 0.01) activity and a decrease in fumarase activity (P less than 0.01) were computed. In relation to the age-dependent variation, maximum LDH activities could be measured at an age of 12-14 years; significantly decreased activities of the glycolytic enzymes could only be found in the youngest group.
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PMID:Skeletal muscle enzyme activities in healthy young subjects. 375 6

Amphibolurus nuchalis were collected in central Australia during mid- (January) and late summer (March). Endurance time at 1 km/h on a motorized treadmill is greater in larger lizards, scaling as M0.65. Maximal O2 consumption (VO2max) scales as M0.96; standard metabolic rate (SMR) scales as M0.83. Factorial aerobic scope thus increases ontogenetically (9.4 at 1 g vs. 15 at 50 g). All organ masses scale allometrically; larger lizards have relatively smaller livers, but larger hearts and thigh muscles. Hematocrit and hemoglobin increase during early ontogeny, but are mass independent in adults. Maximal in vitro catalytic rates were determined for citrate synthase (CS) and pyruvate kinase (PK) in liver, heart, and thigh muscle and for lactate dehydrogenase (LDH) (lactate oxidation) in heart. All enzyme activities (expressed per g tissue) scale positively, except CS in heart. Females exhibit lower SMR and heart CS activity. March animals exhibit elevated endurance, VO2max, heart LDH, and thigh CS and PK activities. Individual variation in endurance correlates with individual differences in heart LDH and thigh CS and/or PK activities. Individual differences in VO2max are partly related to variation in hematocrit.
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PMID:Seasonal, sexual, and individual variation in endurance and activity metabolism in lizards. 382 8

Two groups of Amphibolurus nuchalis, an Australian agamid lizard, were maintained in captivity for 8 wk. The "trained" group was given submaximal exercise at 1 km/h on a motorized treadmill, 30 min/day, 5 days/wk; the treadmill was inclined 10% for the last 5 wk. The "sedentary" group was not exercised. Endurance capacity did not change significantly in either group, but sprint speed decreased in trained lizards. The sedentary group exhibited significant decreases in maximal O2 consumption, standard metabolic rate, and heart mass, but an increase in liver mass. Trained lizards exhibited significant decreases in heart and thigh muscle masses, but significant increases in liver mass, hematocrit, liver pyruvate kinase, and heart citrate synthase activities. It is concluded that the adaptive response to endurance training, typical of mammals, does not generally occur in lizards. Moreover, levels of chronic activity that would elicit adaptive responses in mammals may be excessive for lizards and may induce pathological effects in joints and skeletal muscle. The ecological and evolutionary significance of these conclusions is discussed.
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PMID:Effects of endurance training and captivity on activity metabolism of lizards. 382 9

Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose-6-phosphate, pyruvate, lactate), Krebs cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate), related free amino acids (glutamate, alanine), ammonia, energy store (creatine phosphate), energy mediators (ATP, ADP, AMP) and energy charge potential were evaluated. Furthermore the maximum rate (Vmax) of the following muscular enzyme activities was evaluated in the crude extract and/or mitochondrial fraction: for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase; for the tricarboxylic acid cycle: citrate synthase, malate dehydrogenase; for the electron transfer chain: total NADH cytochrome c reductase, cytochrome oxidase. The rat gastrocnemius muscles were analyzed in normoxia and after repeated, alternate hypoxic and normoxic exposures (12 hours of hypoxia daily; for 5 days). Naftidrofuryl was administered daily at three different doses: 10, 15 and 22.5 mg/kg i.m., 30 min before the beginning of the experimental hypoxia. The biochemical adaptation to intermittent normobaric hypoxic-normoxic exposures was characterized by the decrease of the muscular contents of creatine phosphate, citrate, alpha-ketoglutarate and glutamate. This adaptation occurred in absence of significant changes in the Vmax of the muscle enzymes tested. By naftidrofuryl treatment, in gastrocnemius muscle from hypoxic rats both alpha-ketoglutarate and creatine phosphate contents maintained normal values, while glutamate concentration remained reduced to subnormal values. With the exception of hexokinase, naftidrofuryl treatment did not modify the Vmax of marker enzymes related to energy transduction.
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PMID:Adaptation of skeletal muscle energy metabolism to repeated hypoxic-normoxic exposures and drug treatment. 401 59

Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose-6-phosphate, pyruvate, lactate), Krebs cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate), related free amino acids (glutamate, alanine), ammonia, energy store (creatine phosphate), energy mediators (ATP, ADP, AMP) and energy charge potential were evaluated. Furthermore the maximum rate (Vmax) of the following enzyme activities was evaluated in the crude extract and/or mitochondrial fraction: for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase; for the tricarboxylic acid cycle: citrate synthase, malate dehydrogenase; for the electron transfer chain: total NADH cytochrome c reductase, cytochrome oxidase. The rat gastrocnemius muscles were analysed in normoxia and after normobaric intermittent hypoxia (12 hours continuously daily; for 5 days). Cytidine and/or uridine were administered daily at the dose of 120 mg/kg, i.p., 30 min before the beginning of the experimental hypoxia. The intermittent normobaric hypoxia induced a biochemical adaptation characterized by the decrease of the muscular contents of creatine phosphate, citrate, alpha-ketoglutarate and glutamate. This adaptation occurred in the absence of significant changes in the Vmax of the tested muscle enzymes. In gastrocnemius muscle from hypoxic rats, the two biological pyrimidines tested induced various discrete, but often related, modifications of the contents of some Krebs cycle intermediates (i.e., alpha-ketoglutarate, malate) and related free amino acids (i.e., glutamate, alanine). In any case, the treatment with cytidine and/or uridine did not modify the Vmax of marker enzymes related to energy transduction.
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PMID:Modification of the skeletal muscle energy metabolism induced by intermittent normobaric hypoxia and treatment with biological pyrimidines. 402 89


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