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)

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

1. Percutaneous needle biopsies were obtained from six limb muscles in six horses before and during a training programme of 10 or 15 weeks designed to involve both aerobic and anaerobic work. In a subsequent detraining period, biopsies were also taken after 5 and 10 weeks. 2. Samples were analysed biochemically for enzyme activity of lactic dehydrogenase (LDH), creatine phosphokinase (CPK), aldolase (ALD), citrate synthase (CS), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) and for glycogen content. Fibre typing was carried out histochemically before and 10 weeks after commencement of training. 3. There was a significant increase in the percentage of high myosin ATPase activity pH 9-4/high oxidative (FTH) fibres with a corresponding decrease in high myosin ATPase activity pH 9-4/low oxidative (FT) fibres and low myosin ATPase activity pH 9-4/high oxidative (ST) fibres after 10 weeks training. 4. During training, enzyme activities increased progressively but at different rates with an approximate twofold increase in all of the enzymes except CPK by the end of the training period. Changes in all the muscles studied were similar. Glycogen content increased by approximately 33% which was significant when all the muscles were considered together. 5. A decrease in enzyme activity occurred after 5 weeks detraining. However at 10 weeks a consistent but inexplicable increase in all enzyme levels, except CS again occurred. 6. It is concluded that training increased greatly the activity of enzymes involved in both aerobic and anaerobic metabolism.
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PMID:The effect of training and detraining on muscle composition in the horse. 14 28

1. Biopsies of the extensor hallucis longus (EHL) and gastrocnemius (G) muscles of four captive black bears (Ursus americanus) were obtained prior to denning (PRE), during denning (DEN) and following the Spring arousal (POST). 2. Glycogen, triglyceride and protein concentrations did not differ significantly between the three groups. Likewise, the activity of citrate synthase, a mitochondrial oxidative enzyme, was not significantly different between the three groups. 3. DNA concentrations in DEN samples increased 30% compared to other groups while RNA concentrations were significantly elevated in POST samples. The RNA/DNA ratios were significantly depressed during DEN. 4. These results suggest a degree of muscle atrophy during DEN, with the potential for an increased capacity for muscle protein synthesis following the Spring arousal.
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PMID:Biochemical changes in skeletal muscles of denning bears (Ursus americanus). 172 46

This study examined the effects of a short-term sudden increment in training load on the oxidative capacity, glycogen content and tension-generating ability of rat skeletal muscle. After training on a treadmill 5 dwk-1 for 9 wk (30 m.min-1 6 degrees, 60 min.d-1), rats were randomly divided into a normal training volume (NTV) group (N = 11) and an increased training volume (ITV) group (N = 8). The NTV group were sacrificed 24 h after the last bout of exercise, while the ITV group continued to train for further 6 successive days. Training duration for this latter group was increased to 120 min.d-1 for the first 2 d; 240 min.d-1 for the next 2 d; and 360 min.d-1 for the final 2 d; speed and grade were kept constant. Respiratory capacity (QO2) and citrate synthase activity were increased (P less than 0.05) in both the soleus and plantaris muscles, with no change in the white vastus lateralis muscle of the NTV group when compared to age- matched sedentary controls. Glycogen levels were unchanged in these muscles, but liver glycogen content was greater (231.9 +/- 10.1 vs 156.8 +/- 15.3 umol.g-1 w.w. for the NTV vs age-matched sedentary controls, respectively, P less than 0.05). Peak tetanic tension in the gastrocnemius was not changed by training, or the increased training load. Citrate synthase activity (umol.min-1.g-1) was significantly greater (P less than 0.05) in the plantaris (33.3 +/- 1.0 vs 27.0 +/- 1.7) and soleus muscles (40.5 +/- 2.7 vs 28.4 +/- 1.3) in the ITV vs NTV groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of increased training volume on the oxidative capacity, glycogen content and tension development of rat skeletal muscle. 228 88

The effect of high-intensity trained (6 X 4.5 min at 40 m/min, 15% grade, 2.5-min rest between bouts, 5 days/wk, for 6 wk) on contractile, biochemical, and fatigue properties of the rat diaphragm were examined. The exercise program produced significant elevations in the mitochondrial marker enzyme citrate synthase (mumol X g-1 X min-1) in the soleus (SOL) (27.2 +/- 1.5 vs. 46.7 +/- 2.4; mean +/- SE), deep vastus lateralis (DVL) (40.8 +/- 2.6 vs. 58.3 +/- 2.8), and superficial vastus lateralis (SVL) (8.5 +/- 0.6 vs. 11.4 +/- 0.7). No significant differences were observed in the crural (CRU) (45.9 +/- 2.0 vs. 44.0 +/- 2.3) or ventral costal (VEN) (41.5 +/- 2.0 vs. 45.8 +/- 2.6) diaphragmatic regions. Phosphofructokinase, the rate-limiting enzyme of glycolysis, significantly increased in the SOL (19.0 +/- 0.8 vs. 23.3 +/- 1.3 mumol X g-1 X min-1) and DVL (69.3 +/- 6.0 vs. 86.6 +/- 5.0), but no alterations were seen in the SVL (98.6 +/- 5.7 vs. 106.1 +/- 9.0), CRU (54.4 +/- 2.8 vs. 53.8 +/- 1.5), or VEN (44.7 +/- 2.4 vs. 46.4 +/- 1.4) posttraining. Diaphragm contractile properties, with the exception of an increased rate of fall in twitch tension, remained unchanged after training. Glycogen values were significantly higher in trained diaphragms at rest (6.54 +/- 0.39 vs. 4.86 +/- 0.41 mg/g) and during 1, 5, and 10 min of fatiguing stimulation. During fatigue no differences were observed in force, rate of rise in force, rate of fall in force, muscle lactate, ATP, or creatine phosphate in trained vs. control.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contractile and biochemical properties of diaphragm: effects of exercise training and fatigue. 294 Feb 18

Fibroblast cultures were used to study the effect of crude venom and six venom protein fractions (F2-F7) from Walterinnesia aegyptia on their metabolic activity. This was done by incubation of six fibroblast cultures with 10 micrograms of crude venom for 3 h at 37 degrees C. The activities of phosphofructokinase, lactate dehydrogenase, and citrate synthase were significantly lowered upon incubation with all fractions except F2. Glycogen phosphorylase activity was significantly increased, leading to a significant concurrent drop of glycogen content. This effect was only seen for fractions F3 and F5. Creatine kinase activity and cellular ATP levels rose significantly upon incubation with all venom proteins except fractions F2 and F7. Increases were seen for aspartate and alanine aminotransferases by all venom proteins except fractions F2 and F4. Incubation of cell sonicates with all the venom proteins did not significantly alter activities of any of the parameters. Thus, fibroblasts in culture under such conditions appear to mobilize glycogen, phosphocreatine, and protein for ATP production to compensate for decreased glucose.
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PMID:The effect of the desert cobra (Walterinnesia aegyptia) crude venom and its protein fractions on the metabolic activity of cultured human fibroblasts. 881 58

We tested the hypothesis that improved ischemia tolerance in an isolated working rat heart preparation can be achieved by interventions other than ischemic preconditioning. Hearts were perfused at near-physiological workload with bicarbonate buffer containing glucose (10 mM). A preischemic period of 25 min was followed by 15 min of global ischemia and 30 min of reperfusion under preischemic conditions. Hearts came from either fed or fasted animals (groups 1 and 2). In group 3 lactate (10 mM) and insulin (10 mU/ml) were added to the perfusate of fasted animals. In group 4 hearts from fed animals were perfused with glucose (10 mM) and were ischemically preconditioned by one cycle of ischemia between 10 and 15 min of the preischemic perfusion. Cardiac power and glucose uptake were measured continuously to assess functional and metabolic recovery. In addition, we measured the time to return of aortic flow. Glucose metabolites and the ratio of latent of free citrate synthase activity (citrate synthase ratio, a marker for the structural integrity of mitochondria) were determined at selected time points. Groups 2, 3, and 4 recovered significantly faster than group 1, whereas recovery of power showed an improvement in groups 3 and 4 only. In addition, there was an early increase in glucose uptake during reperfusion in these two groups, suggesting an early need for glucose substrate. Glycogen levels decreased with ischemia in all groups and returned to preischemic levels in groups 2, 3, and 4. The citrate synthase ratio was low in the control group and preserved in the groups showing improved functional recovery. We conclude that metabolic interventions may be as effective as ischemic preconditioning in protecting the heart from ischemic injury.
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PMID:Fasting, lactate, and insulin improve ischemia tolerance in rat heart: a comparison with ischemic preconditioning. 892 65

The purpose of this study was to examine the relationship between skeletal muscle GLUT-4 protein and postexercise glycogen storage in human subjects fed adequate carbohydrate. Eleven men completed 2 h of cycling, and a biopsy of the vastus lateralis was performed immediately after exercise cessation for the determination of muscle GLUT-4 protein and glycogen concentrations, glycogen synthase activity, and citrate synthase activity. The subjects ingested meals providing 2.0 g carbohydrate/kg body weight at 0, 2, and 4 h postexercise, and a second biopsy was performed 6 h postexercise. Muscle glycogen concentration increased significantly during the 6-h recovery period (glycogen immediately postexercise, 27.2 +/- 5.4 mmol/kg wet weight; glycogen storage, 52.4 +/- 2.9 mmol x kg wet weight-1 x 6 h-1; P<0.05). Glycogen storage during recovery was directly related to GLUT-4 protein (2.20 +/- 0.33 arbitrary standard units; r = 0.63; P<0.05) and inversely related to glycogen immediately postexercise (r = -0.70; P < 0.05). A direct correlation existed between glycogen storage during recovery and the activity of the I form of glycogen synthase (r = 0.60; P < 0.05). These results suggest that muscle GLUT-4 protein concentration, as well as factors relating to glucose disposal, may affect postexercise glycogen storage in humans fed adequate carbohydrate.
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PMID:Skeletal muscle GLUT-4 and postexercise muscle glycogen storage in humans. 892 77

To study the effects of nandrolone laureate (19-nortestosterone) on muscle hypertrophy and concentration of androgen receptors (AR), biopsy specimens were taken from the middle gluteal muscle of 6 Finnhorse trotters (geldings and mares) undergoing training before, immediately after, and 13 weeks after a 14-week treatment with nandrolone. Another 6 similarly trained horses served as controls. An additional 10 mares and 10 geldings were used to study annual variation in muscle concentration of AR. AR was immunohistochemically localized in the nuclei. AR concentration remained constant during the first 14 weeks of the study, but increased significantly during the 13-week follow-up period in both groups. This finding can be explained by the annual variation in AR. In the anabolic steroid (AS)-treated horses, but not in the controls (C), the cross-sectional area of the type I fibres increased significantly during the treatment period, and the percentage of type IIA fibres correlated positively with AR concentration at the end of nandrolone treatment. In the AS group, the concentration of DNA decreased during the 13-week follow-up period, and the percentage of H-chains in the isoenzymes of LDH increased. Protein concentration increased in both groups during the follow-up period. Glycogen content and the activity of citrate synthase in muscle during the study remained unchanged. It can thus be concluded that AS produce differing effects on type I and type II fibres, and the AR concentration in equine muscle may contribute to the change observed in the middle gluteal muscle.
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PMID:Androgen receptors and skeletal muscle composition in trotters treated with nandrolone laureate. 942 51

We investigated effects of hypertension and early development on myocardial energy metabolism as reflected by maximal enzyme activities, glucose transporter content, and endogenous substrates in female Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Left ventricular hypertrophy and systolic hypertension were evident in SHR at 6 weeks of age and these differences increased at 14 and 22 weeks of age. 3-Hydroxyacyl-CoA dehydrogenase (HOAD) activity in the left ventricle was 18% lower in 6-week-old rats than both 14- and 22-week-old rats, but not different between WKY rats and SHR. Hexokinase activity was 15% lower in 6-week-old SHR than WKY rats and decreased progressively with age in both strains. Glucose transporter (GLUT) 1 content was nearly twofold greater in 6-week-old rats than both 14- and 22-week-old rats. We found no difference in citrate synthase activity or GLUT4 content among groups. Glycogen concentration was 44% lower in SHR than WKY rats, whereas triglyceride was slightly (16%) higher in SHR than WKY rats. Older animals had higher levels both glycogen and triglyceride than younger animals. We conclude that the left ventricle of both SHR and WKY rats may change from predominantly glucose to fatty acid oxidation for energy production during early development.
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PMID:Changes in cardiac energy metabolism during early development of female SHR. 1104 Nov 61


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