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)

Repeated injections of rat with 1-thyroxine (50 microgram/kg daily for 5 five-day weeks) retarded the weight gain of the animals and increased the absolute and relative size of the heart, adrenals and interscapular brown adipose tissue. In the myocardium and thigh muscle, thyroxine treatment resulted in elevated activity of oxidative enzymes, succinate dehydrogenase, malate dehydrogenase and citrate synthase, while the activities of glycolytic enzymes remained unchanged. Glycogen content of the heart was decreased following thyroxine regime. In the brown fat, on the other hand, thyroxine injections resulted in a reduction of the activity of oxidative enzymes. This reduction can be accounted for by the decreased protein (enzyme) content of the tissue due to deposition of fat. Furthermore, thyroxine treatment delayed the body cooling of the rats swimming in water at 25 degrees C and enhanced hyperthermic response to injected noradrenaline. All these changes, which were not observable in rats treated with daily alprenolol (20 mg/kg) injections, were as pronounced in rats injected with alprenolol together with thyroxine as in rats injected with thyroxine only. It is concluded that beta blockers do not antagonize the metabolic changes due to hyperthyroidism.
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PMID:Alprenolol fails to antagonize the metabolic changes following repeated thyroxine injections in the rat. 2 61

The metabolic effects on rat cardiac and skeletal muscle of a strenous program of swimming, of cold acclimation and of isoprenaline treatment (0.3 mg/kg daily for 5 five-day weeks) were compared. Exercised and cold-exposed rats gained less body weight than did controls or isoprenaline-treated rats. In all treated groups the heart and the intercapular brown adipose tissue hypertrophied. The size of the adrenals increased only in isoprenaline-treated animals. Cold-acclimation and physical training increased and isoprenaline treatment reduced or did not affect the activities of succinate dehydrogenase, malate dehydrogenase and citrate synthase of cardiac muscle. In the skeletal muscle all treatments resulted in increased activities of these enzymes. Of the anaerobic enzymes analysed, only the activity of hexokinase increased in response to the treatements used. This increase was the same in cardiac as in skeletal muscle, but it was significantly greater with isoprenaline-treatment than with training or with cold-acclimation. The activities of lactate dehydrogenase and phosphofructokinase did not differ significantly. All treatments improved cold resistance, but only swimming exercise and cold acclimation significantly increased tolerance to exercise. It is concluded that prolonged stimulation of adrenergic beta-receptors by catecholamines is responsible for the metabolic changes observed.
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PMID:Comparison of the effects of physical exercise, cold acclimation and repeated injections of isoprenaline on rat muscle enzymes. 12 87

The effect of prolonged digoxin treatment (1 mg/kg day for 8 days) on the activity levels of some enzymes of energy metabolism (phosphofructokinase, lactate dehydrogenase, citrate synthase, succinate dehydrogenase) in rat myocardium was studied. In the control animals receiving the solvent mixture (glycerol:ethanol:water in 1:1:1) a transient decrease in the lactate dehydrogenase and citrate synthase activity levels was observed. In the hearts of digoxin treated rats the level of activity of phosphofructokinase was permanently lowered by the fourth day and the level of activity of citrate synthase permanently increased after the first day of treatment. A transient increase in the activity level of succinate dehydrogenase in the myocardium of digoxin treated animals was seen between days 1 and 6. In this study a permanent decrease in phosphofructokinase and an increase in citrate synthase activity levels in rat heart muscle was noted during prolonged digoxin treatment.
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PMID:Enzyme activities of myocardial energy metabolism during prolonged digoxin treatment in rats. 14 96

The activities of five mitochondrial enzymes tested in liver from patients with Reye's syndrome were measured. Citrate synthase, glutamic dehydrogenase, succinic dehydrogenase, pyruvate carboxylase, and pyruvate dehydrogenase were all outside of the range shown by control samples and well below them in activity. The activity of two extramitochondrial enzymes, glucose-6-phosphatase, which is a microsomal enzyme, and fructose-1,6-diphosphatase, which is a soluble enzyme, were in the normal range in samples from Reye's syndrome patients. In both muscle and brain the activities of the mitochondrial enzyme, citrate synthase, glutamic dehydrogenase, and succinic dehydrogenase were all within the control range. Pyruvate dehydrogenase was found to be normal in muscle from these patients.
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PMID:Reye's syndrome: preservation of mitochondrial enzymes in brain and muscle compared with liver. 21 43

A crude mitochondrial fraction (M) derived from manually disrupted cerebellar tissue and enriched in choline acetyltransferase (ChAT) activity was fractionated by centrifugation in discontinuous and continuous sucrose gradients. Further purification of 'cholinergic' synaptosomes was achieved (relative specific activity (RSA) of ChAT greater than 3), but the overlap with other synaptosomal populations was still considerable. Hand-homogenized cerebella processed through the full fractionation procedure described here and in previous papers yielded preparations enriched in certain neuronal structures and a fraction in which 'heavy' free mitochondria was concentrated. To characterize these preparations the activities of two transmitter enzymes (CHAT and glutamate decarboxylase, GAD) and 6 mitochondrial enzymes (succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), monoamine oxidase, citrate synthase, fumarase and GABA-aminotransferase) were determined. The distribution of the transmitter enzymes was clearly different in the preparations containing various neuronal structures. The GAD:ChAT RSA ratio was 2.4 for the glomerulus particles, 1.3 for the molecular layer fragments, 0.6 for the myelinated axon segments, and 0.2 for the 'cholinergic' synaptosomes. The mitochondrial enzyme profile of the preparations comprising mainly neuronal structures differed markedly from that of the 'free' mitochondrial fraction. Notably the latter was greatly enriched in GDH (RSA 5.6), whereas the SDH:GDH RSA ratio was relatively high in the former preparations. Nevertheless there were notable differences in the enzyme profile of the fractions of predominantly neuronal origin indicating that the enzyme composition of mitochondria of neuronal processes is not uniform.
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PMID:Subcellular fractionation of rat cerebellum: separation of synaptosomal populations and heterogeneity of mitochondria. 21 84

Rats were treated by daily alprenolol (10, 20 and 50 mg/kg) injections for 5 days a week for 4 weeks. At 20--21 degrees C alprenolol treatment retarded the weight gain of the animals and increased the weight of the adrenals. These changes were not seen at 29 degrees C. The reduction in size and fat content of the interscapular brovin adipose tissue in drug-treated rats was independent of experimental temperature. At 20--21 degrees C prolonged beta-blockade did not cause any changes in the enzymes of the energy metabolism. At 29 degrees C, however, alprenolol treatment antagonized the decrease in activity of oxidative enzymes (succinate dehydrogenase, malate dehydrogenase, citrate synthase) and the decrease in protein concentration of the cardiac muscle. In skeletal muscle alprenolol treatment significantly decreased the activities of oxidative enzymes and antagonized the rise in the activity of lactate dehydrogenase resulting from warm acclimation. The increased activities of oxidative enzymes in interscapular brown adipose tissue of aprenolol treated rats were coupled with an increase in protein concentration of the tissue. Although these changes were more marked at 29 degree C they were observable at 20--21 degree C, too. The difference in the drug effects at 20--21 degrees C and 29 degrees C can be accounted for by the compensatory catecholamine release at the lower temperature, due to impaired thermoregulatory capacity after alprenolol. Prolonged beta blockade decreased the exercise tolerance and cold tolerance of the rats. An increased response of the diastolic blood pressure to an alpha-adrenergic drug, noradrenaline, and a decreased response to a beta-adrenergic drug, isoprenaline, in alprenolol-treated rats indicates a shift from beta- to alpha-receptors.
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PMID:Effect of prolonged beta-blockade on energy metabolism and adrenergic responses in the rat. 59 3

1. Enzyme activities (units/g wet wt.) were determined in the caput and cauda epididymidis and in epididymal spermatozoa of the rat. 2. The activity of most enzymes in the cauda was between 50 and 100% of that in the caput, except that ATP citrate lyase was barely detectable in the cauda. 3. Spermatozoa, unlike epididymal tissue, contained sorbitol dehydrogenase but lacked ATP citrate lyase. NADP+-malate dehydrogenase, mitochondrial glycerol 3-phosphate dehydrogenase, succinate dehydrogenase, carnitine acetyltransferase and citrate synthase were 5 to 400 times as active in spermatozoa as in epididymal tissue. 4. 2-Oxoglutarate dehydrogenase was the least active member of the tricarboxylic acid cycle in all tissues and most closely matched the measured flux through the cycle. 5. The concentrations of hydroxyacyl-CoA dehydrogenase and carnitine palmitoyltransferase were equivalent to the more active enzymes of the tricarboxylic acid cycle, indicating the capacity for extensive lipid oxidation, and the presence of 3-hydroxybutyrate dehydrogenase suggests that these tissues can also oxidize ketone bodies. 6. Transfer of reducing equivalents from cytoplasm to mitochondrion is unlikely to occur by means of the glycerol phosphate cycle because mitochondrial glycerol 3-phosphate dehydrogenase is relatively inactive in epididymal tissue, whereas the cytoplasmic enzyme has little activity in spermatozoa, but transfer may be accomplished by the malate-aspartate shuttle. 7. Transfer of acetyl units from mitochondrion to cytoplasm could be effected by the pyruvate-malate cycle in the caput of androgen-maintained rats, but not in the other tissues because of the low activity of ATP citrate lyase. Acetyl unit transfer could take place via acetylcarnitine, mediated by carnitine acetyltransferase. 8. Castration resulted in a decrease in the concentration of nearly all enzymes, although subsequent administration of testosterone restored concentrations to values similar to those in animals maintained by endogenous androgen. The extent to which enzyme concentration was changed by an alteration in androgen status was highly variable, but was most marked in the case of pyruvate carboxylase.
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PMID:Activity and androgenic control of enzymes associated with the tricarboxylic acid cycle, lipid oxidation and mitochondrial shuttles in the epididymis and epididymal spermatozoa of the rat. 72 83

Two populations of mitochondria were observed upon ultrastructural examination of cardiac muscle tissue, one located directly beneath the sarcolemma (subsarcolemmal mitochondria) and another between the myofibrils (interfibrillar mitochondria). Subsarcolemmal mitochondria were released by treatment of heart muscle with a Polytron tissue processor, while interfibrillar mitochondria were released by nagarse digestion of the remaining tissue. These results were supported by electron microscopy of Polytron-treated heart tissue showing rupture and loss of sarcolemma with release of the underlying mitochondria but with retention of intact mitochondria between the myofibrils. Electron microscopy of the isolated mitochondria indicated that both mitochondrial types maintained their structural integrity throughout the isolation procedure. Specific activities of succinate dehydrogenase and citrate synthase were higher in the interfibrillar mitochondria as compared to the subsarcolemmal mitochondria, while those of carnitine palmitoyltransferase and alpha-glycerophosphate dehydrogenase were nearly the same in both. Interfibrillar mitochondria oxidized all substrates tested approximately 1.5 times faster than did the subsarcolemmal mitochondria. Thus the two mitochondrial types differed not only in their respective locations in the cell, but also in certain biochemical properties.
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PMID:Biochemical properties of subsarcolemmal and interfibrillar mitochondria isolated from rat cardiac muscle. 92 18

Carbon-14 was incorporated into oxalate and CO2 from either citrate-1,5-14C, succinate-1,4-14C, or fumarate-1,4-14C by cultures of Aspergillus niger pregrown on a medium which contained glucose as the sole carbon source and which did not allow citrate accumulation. In cell-free extracts of mycelium forming oxalate and CO2 from added citrate the following enzymes of the tricarboxylic acid (TCA) cycle were identified: citrate synthase CE 4.1.3.7), aconitate hydratase (EC4.2.1.3), NAD and NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41, 1.1.1.42), (alpha-oxoglutarate dehydrogenase (EC 1.2.4.2), succinate dehydrogenase (EC 1.3.99.1), fumarate hydratase (EC 4.2.1.2), and malate dehydrogenase (EC 1.1.1.37). The in vitro activity of aconitate hydratase and of NADP-dependent isocitrate dehydrogenase was shown to be almost identical to the rate of in vivo degradation of citrate or to exceed this rate. The degradation of citrate to oxalate was inhibited completely by 9 mM fluoroacetate. It is concluded that the TCA cycle is involved in the formation of oxalate from citrate.
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PMID:Oxalate accumulation from citrate by Aspergillus niger. II. Involvement of the tricarboxylic acid cyclase. 115

The effects of L-carnitine on respiratory chain enzymes in muscle of long distance runners were studied in 14 athletes. These subjects received placebo or L-carnitine (2 g orally b.i.d.) during a 4-week period of training. Athletes receiving L-carnitine showed a significant increase (p < 0.01) in the activities of rotenone-sensitive NADH cytochrome c reductase, succinate cytochrome c reductase and cytochrome oxidase. In contrast, succinate dehydrogenase and citrate synthase were unchanged. No significant changes were observed after placebo administration. The levels of both total and free carnitine from athletes receiving placebo were significantly decreased (p < 0.01) after treatment. By contrast, total and free carnitine levels were markedly increased (p < 0.01) after supplementation with L-carnitine. Our results suggest that L-carnitine induces an increase of the respiratory chain enzyme activities in muscle, probably by mechanisms involving mitochondrial DNA.
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PMID:Respiratory chain enzymes in muscle of endurance athletes: effect of L-carnitine. 132 42


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