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)

Young rats maintained on an iron-deficient diet developed severe anemia and had large decreases in the levels of the iron-containing flavoproteins and cytochromes of the mitochondrial respiratory chain in skeletal muscle. In contrast, the levels of a number of mitochondrial matrix marker enzymes, including citrate synthase, isocitrate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, 3-ketoacid-CoA transferase, and aspartate aminotransferase, increased in red skeletal muscle but not in white muscle. Phosphocreatine concentration was decreased and inorganic phosphate concentration was increased in soleus muscle frozen in situ. We hypothesize that the increase in mitochondrial matrix enzymes reflects a stimulus to mitochondrial biogenesis in posture-maintaining and weight-bearing red muscle fibers in severely iron-deficient rats. It is our working hypothesis that this stimulus to mitochondrial biogenesis arises from mild activity of the red fibers and is due to the same perturbation in cellular homeostasis that is normally caused by vigorous exercise or hypoxia. In iron deficiency, the stimulus to mitochondrial biogenesis can induce an increase in only those enzymes not prevented from increasing by iron deficiency, resulting in formation of mitochondria of grossly abnormal composition.
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PMID:Induction of an increase in mitochondrial matrix enzymes in muscle of iron-deficient rats. 347 8

Old rats have a decreased hindlimb muscle respiratory capacity and whole-body maximal O2 consumption (VO2 max). The decline in spontaneous physical activity in old rats might contribute to these age-related changes. The magnitude of the age-related decline is not uniform in all skeletal muscle respiratory enzymes, and the decrease in palmitate oxidation is particularly great. This study was designed to determine if young and old rats subjected to the same exercise-training protocol would attain similar values for VO2 max and several markers of muscle respiratory capacity. Four- and 18-mo-old Fischer 344 rats underwent an identical 6-mo program of treadmill running. After training, both age groups had increased VO2 max above sedentary age-matched controls. However, the old trained rats had a lower VO2 max than identically trained young rats. In contrast to VO2 max, the two trained groups attained similar values for gastrocnemius citrate synthase, cytochrome oxidase, 3-hydroxyacyl-CoA dehydrogenase, palmitate oxidation, and total carnitine concentration. Thus, when the young and old rats performed an identical exercise protocol within the capacity of the old animals, differences in skeletal muscle respiratory capacity were eliminated. The dissimilarity in VO2 max between the identically trained groups was apparently caused by age-related differences in factors other than muscle respiratory capacity.
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PMID:Muscle respiratory capacity and VO2 max in identically trained young and old rats. 362 29

The purpose of this study was to investigate alterations in structural and functional properties in the soleus (SOL) and extensor digitorum longus (EDL) muscles of rats after 1, 2, and 5 wk of tail suspension. Maximal O2 uptake was 19% lower after 5 wk suspension. Loss of muscle mass was greater in SOL (63%) than in EDL (22%) muscle. A reduction of type I distribution was accompanied by an increase of intermediate fiber subgroups (int I in SOL, int II in EDL). The cross-sectional area of all three fiber types was reduced by hypokinesia. The decrease in capillaries per fiber in SOL was greater than the decrease in citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities after 5 wk. No alteration in lactate dehydrogenase activity was noted. In EDL, no changes in fiber area, capillarization, and enzymatic activities occurred. Energy charge remained unchanged (0.91) whatever the muscle. These results suggest that type I fibers showed an earlier and greater susceptibility than type II fibers to suspension which is also accompanied by a decreased aerobic capacity.
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PMID:Structural and functional responses to prolonged hindlimb suspension in rat muscle. 365 14

The capacity for energy production was evaluated in male, Fischer 344 rats as they advanced from adulthood through senescence. At 10 months of age, the animals were divided into three groups: sedentary, fed ad libitum (S); exercised by treadmill running, fed ad libitum (E); and sedentary, caloric restricted by alternate day feeding (R). Activities of selected enzymes, ADP-stimulated respiration and levels of cytochromes, were determined in homogenates of liver and gastrocnemius muscle prepared from young controls (10-month old S) and 18-, 24-, and 30-month old animals. In liver, age-linked decrements were found in the activities of 3-hydroxyacyl-CoA dehydrogenase (S, E, and R) and citrate synthase (S), and in cytochrome c content (S and E), whereas substrate-catalysed oxidations were unaffected. In the gastrocnemius muscle (S, E, and R), respiration, activities of enzymes of the Krebs cycle and glycolysis, and cytochrome content were decreased after the age of 18 months. Oxidative capacity was increased in muscle through exercise (about 40%) and in liver by food restriction (about 20%). Body and soleus muscle mass declined similarly in all groups (about 14% from 30 to 18 months of age), whereas the loss of weight in the gastrocnemius muscle was much greater (34%). The data indicate that energy metabolism in the senescent animal is competent to meet its needs and age-related declines in energy metabolism are secondary to the aging process.
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PMID:Bioenergetics in the aging Fischer 344 rat: effects of exercise and food restriction. 366 72

The purpose of this study was to compare the effects of spontaneous recovery or recovery by treadmill training (180 min/day, 5 days/wk, 30 m/min for 8 wk) on maximal O2 uptake (VO2max), histochemical and biochemical muscular properties (soleus), of rats subsequent to 5 wk of hindlimb suspension. Spontaneous recovery reversed the 15% reduction in VO2max, whereas training posthypokinesia induced a 20% increase over control values. In the spontaneous recovery group, both citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities, decreased by hypokinesia (-40%), increased but remained 20% below the control level. In the training posthypokinesia group, an increase of these activities over control occurred (+50 and +20%, respectively). Recovery or training led to a 100% type I distribution in soleus muscle and to a recovery of all fibers' cross-sectional areas. In the spontaneous recovery group, capillaries per fiber, decreased by 46%, returned to the normal range. In the training posthypokinesia group, training induced an increase in capillaries per fiber above their control values (+23%). These results point to the plasticity of the muscle and indicate the necessity of a posthypokinesia training program for recovery of the total oxidative enzyme capacity.
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PMID:Effect of spontaneous recovery or retraining after hindlimb suspension on aerobic capacity. 369 9

The superficial muscle fibres in the proximal part of the closer muscle in the crab Eriphia can be separated into four fibre groups (I-IV) on the basis of electrophysiological and histochemical characteristics. The activity levels of glyceraldehydephosphate dehydrogenase (GAPDH), lactate dehydrogenase (LDH), citrate synthase (CS), NADP-isocitrate dehydrogenase (IDH) and 3-hydroxyacyl-CoA dehydrogenase (HAD), determined in single electrophysiologically identified fibres, differed significantly among the different fibre groups. In addition, fibres belonging to the same group, with similar electrophysiological characteristics, demonstrated variability with regard to metabolic enzyme activities. Nevertheless, comparison of absolute enzyme activities and enzyme activity ratios permitted the discrimination of at least three groups. These groups corresponded with those defined according to electrophysiological and histochemical characteristics. The group I fibres (tonic fibres) are intermediate in oxidative potential and show the lowest values of glycolytic enzymes. The group II and group III fibres can be regarded as fast oxidative fibres. The high ratio between activity levels of enzymes for glycolytic and oxidative metabolism found for group IV fibres (fast fibres) demonstrated that this group depends strongly on anaerobic metabolism.
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PMID:Enzyme activities in single electrophysiologically identified crab muscle fibres. 370 50

3-Hydroxyacyl coenzyme A (CoA) dehydrogenase-binding protein was solubilized from inner mitochondrial membrane by using taurodeoxycholate at high ionic strength. The binding protein was isolated from the suspension using 3-hydroxyacyl-CoA dehydrogenase affinity chromatography. The protein eluted from the affinity column had a molecular weight of approximately 150,000, as determined by gel filtration. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the protein is a dimer consisting of 69,000 and 71,000 molecular weight subunits. The enzyme binding capacity of this protein was tested with a polyethylene glycol precipitation method: 0.5 mg of enzyme could be precipitated together with 1 mg of binding protein, showing that 1 mol of binding protein binds 1 mol of enzyme. This protein had no affinity toward malic dehydrogenase, citrate synthase, and fumarase. The approximately 2-fold increase in the 3-hydroxyacyl-CoA dehydrogenase activity when it was measured in the presence of the binding protein is additional evidence of enzyme-binding protein interaction. When incorporated into liposomes, the binding protein retained its ability to bind 3-hydroxyacyl-CoA dehydrogenase, but did not bind malic dehydrogenase, citrate synthase, and fumarase. These results suggest that the protein isolated by us has a specific function in anchoring a beta-oxidation enzyme to the matrix surface of the mitochondrial membrane.
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PMID:Isolation and characterization of 3-hydroxyacyl coenzyme A dehydrogenase-binding protein from pig heart inner mitochondrial membrane. 377 31

The paired tracer-dilution method applied to the rat hindlimb perfusion technique was used to investigate the effect of a 10-wk treadmill training program on glucose transport and net uptake in rat skeletal muscles. Glycolytic and oxidative marker enzyme activities were determined. The rats were allowed to rest for 2 days before the experiments were carried out, since long-term adaptive changes were to be studied. The endurance training program caused a 30% increase in the 3-hydroxyacyl-CoA dehydrogenase and citrate synthase activities, but no changes in glycolytic enzymes, confirming that endurance training provokes an increase in the oxidative capacity of the muscle. No significant differences were found in glucose transport rate or net glucose uptake between trained and sedentary rats, which indicates that no long-term adaptive changes in glucose utilization occur in response to endurance training.
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PMID:Influence of endurance training on glucose transport and uptake in rat skeletal muscle. 377 98

The effects of training on skeletal muscle composition were studied in four Standardbred geldings given a seven week submaximal treadmill training programme. Before the start of training, muscle biopsies were collected from the left middle gluteal muscle for the determination of muscle fibre types, oxidative capacity and capillary numbers using histochemical techniques. The concentrations of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase (HAD), lactate dehydrogenase and total muscle glycogen were measured using fluorometric methods. Muscle biopsy samples were repeated after one, three, five and seven weeks of training and the same measurements performed. No significant changes were found in muscle fibre types or capillary numbers as a result of training, although there was an increase in the oxidative capacity of the Type IIB fibres after seven weeks training. After seven weeks of training there were also increases in the concentrations of citrate synthase and HAD and a decrease in lactate dehydrogenase. Before commencement of training the horses underwent a standardised submaximal exercise test and muscle glycogen concentrations were measured before and immediately after the exercise. This procedure was repeated after one, three, five and seven weeks of training. A progressive decrease in the rate of glycogen utilisation occurred throughout the period of training, which by seven weeks was 36 per cent lower than that before training.
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PMID:Effects of a submaximal treadmill training programme on histochemical properties, enzyme activities and glycogen utilisation of skeletal muscle in the horse. 407 45

Sixteen male subjects (20-31 yr) trained for 8 wk on cycle ergometers. Eight of the subjects were treated during the training period with the beta-adrenoceptor blocker propranolol (160 mg/day). During all pre-and posttraining tests, subjects were uninfluenced by the medication. Training-induced increases in VO2max and decreases in blood lactate and norepinephrine concentrations at submaximal exercise were not different between the beta-blockade and the placebo groups. The activities of the mitochondrial enzymes citrate synthase (CS), succinate dehydrogenase (SDH), cytochrome c oxidase (Cyt-c-ox), and 3-hydroxyacyl-CoA dehydrogenase (HAD) in the quadriceps femoris muscle increased significantly (P less than 0.01) with training (beta-blockade group, +47, +33, +38, and 22%; placebo group, +75, 70, +87, and +63%, respectively). Cyt-c-ox and HAD increased significantly more in the placebo group than in the beta-blockade group, while a tendency to an increase was noted for SDH. Muscle capillary density increased similarly (+17-19%) with training in the two groups (P less than 0.01). In conclusion, subjects training under the influence of a therapeutic level of beta-adrenergic blockade show marked increases in both the respiratory capacity and the capillary supply of the engaged skeletal muscles. However, the increase in muscle mitochondrial enzymes may be less apparent than in the normal state.
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PMID:Beta-adrenergic blockade and training in human subjects: effects on muscle metabolic capacity. 608 81


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