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)

Endomyocardial biopsies were taken from the apex of the left ventricle in 15 patients operated on for aortic valve disease or ischaemic heart disease and from papillary muscles in six patients operated on for mitral valve disease. Activities of cardiac phosphofructokinase (PFK), total lactate dehydrogenase (LD), its isoenzyme LD1, aspartate aminotransferase (ASAT), total creatine kinase (CK), its isoenzyme MB, citrate synthase (CS) and myoglobin content (MYO) were related to the angiographically determined left ventricular function. Activities of total LD, PFK and PFK/CS ratio were lower in patients with decreased, than in those with normal, left ventricular function. Myoglobin content and activities of CS and ASAT were not related to left ventricular function. It is suggested that depressed left ventricular contractility is associated with a decreased glycolytic capacity while the oxidative capacity is mainly unaltered.
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PMID:Key enzymes of myocardial energy metabolism in patients with valvular heart disease: relation to left ventricular function. 297 29

The glycolytic and aerobic oxidative capacity in skeletal muscle was investigated to reveal if the decrease seen in muscle protein synthesis is accompanied by a fall in the enzymatic capacity to oxidize substrates. Six patients undergoing elective abdominal surgery were investigated by percutaneous muscle biopsies taken before surgery and on the first and third postoperative days. Protein synthesis as assessed by the polyribosome concentration was 40% lower on the third day postoperatively than before surgery (p less than 0.01). The glycolytic and oxidative capacity was evaluated by determining the activity of eight key enzymes in the intracellular oxidative metabolism, namely total creatine kinase (CK), the isozymes CK-MB and mitochondrial CK, lactate dehydrogenase, citrate synthase, aspartate aminotransferase, and phosphofructokinase, and also the concentration of myoglobin. None of these parameters were affected in the immediate postoperative period independently of the provision of nutritional support. It was concluded that the decrease in protein synthesis is not accompanied by a concomitant decline in the enzymatic oxidative capacity in skeletal muscle in the period immediately following elective surgery.
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PMID:Enzymatic capacity and protein synthesis in human muscle postoperatively. 314 5

A morphometric analysis was performed on horse muscle tissue to quantify mitochondrial distribution relative to capillaries. Samples of M. vastus medialis, M. semitendinosus, M. masseter and M. cutaneus thoracicus were preserved in a glutaraldehyde fixative for electron microscopy, or frozen for biochemical and histochemical analysis. These four muscles varied from highly oxidative in type, consisting nearly completely of type I fibres, in masseter, to highly glycolytic, primarily type IIb fibres, in cutaneus. In all four muscles, mitochondria were found in highest volume density near capillaries at the fibre border, with a sharp decline in volume density towards the fibre centre. This distribution was independent of myoglobin concentration, muscle fibre type and the activities of three key metabolic enzymes, citrate synthase, 3-OH-acyl-CoA dehydrogenase and lactate dehydrogenase.
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PMID:The similarity of mitochondrial distribution in equine skeletal muscles of differing oxidative capacity. 320 68

A new method was developed to determine myoglobin (Mb) contents in as least as 5 mg of murine skeletal muscles. The method was a modification of Reynafarje's spectroscopic technique and was based on the Soret absorptions at 416 and 422 nm of the muscle extract. Mb contents in the skeletal and cardiac muscles increased with age and were widely different from muscle to muscle. The contents in most of the 13 muscles examined at the 30th week of age were less than 1.5 mg/g wet muscle, but the cardiac, soleus and gracilis muscles showed exceptionally high values of 2.2-6.0 mg/g. The relative content of one muscle to the other was the same independent of differences in age, strain and sex. There was a positive correlation between the muscle Mb contents and citrate synthase activity (r = 0.930). Young male mice (5 wk-old) were endurance-trained by a gradual load-increment program on treadmill for 10 weeks (5 days/week), but the training had no effects on the Mb contents. No substantial alteration of the contents was also observed in the limbs immobilized by plaster-fixation for 4 weeks.
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PMID:[Determination of age- and exercise-dependent changes in myoglobin contents in murine skeletal and cardiac muscles]. 324 71

The effect of endurance training on skeletal muscle myoglobin concentration in man was investigated. 8 healthy sedentary males (20-31 yrs) trained on cycle ergometers 40 min/day, 4 days a week for 8 weeks. The work consisted of continuous exercise at a work load that during the last 5 weeks corresponded to 75% of the pretraining maximal oxygen uptake (VO2 max). The training program resulted in a 7% increase in VO2 max (p less than 0.01). The activities of the mitochondrial enzymes citrate synthase (CS), succinate dehydrogenase (SDH) and cytochrome c oxidase (Cyt-c-ox) in the quadriceps femoris muscle, as indicators of muscle respiratory capacity, increased by 62-82% (p less than 0.01). The metabolic adaptation of skeletal muscle was further indicated by a 17% increase in the work load corresponding to a blood lactate concentration of 4 mmol/l, as determined by a progressive exercise test (p less than 0.05). There was, however, no change in the myoglobin concentration of the thigh muscle with training (-1%, NS). It is suggested that endurance exercise in man at 75% of the maximal oxygen uptake does not severely tax the functions of myoglobin in skeletal muscle.
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PMID:Dissociation of training effects on skeletal muscle mitochondrial enzymes and myoglobin in man. 630 98

An attempt was made to determine the relationship of myoglobin content to specific fiber types in human muscle. Biopsies were obtained from biceps brachii, vastus lateralis, and gastrocnemius muscles of untrained subjects and from the vastus lateralis muscle of a highly trained athlete at peak training and at intervals of no training (detraining). Individual muscle fibers were assayed, by quantitative microanalytical methods, for myoglobin, lactate dehydrogenase, malate dehydrogenase, citrate synthase, beta-hydroxyacyl-coenzyme A dehydrogenase, and adenylokinase activities all on the same fiber. The enzyme levels were used to classify the fibers into type I or II. The results show that the content of myoglobin in human muscle does not differ greatly between fiber types in contrast to other species. The type II fibers contained, on the average, at least two-thirds as much myoglobin as type I fibers. The concentration of myoglobin did not change in either fiber type during detraining (84 days), despite marked changes in lactate dehydrogenase, adenylokinase and the three oxidative enzymes.
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PMID:Myoglobin levels in individual human skeletal muscle fibers of different types. 649 Dec 55

The extractable total activities of lipoamide dehydrogenase (LIPDH), citrate synthase (CS), and beta-hydroxyacyl-CoA-dehydrogenase (HADH) were determined in different muscles (longissimus dorsi, semimembranosus, diaphragma) from cattle and pigs, and in the breast and leg muscles from chicken and ducks. The subcellular distribution of these enzymes was elucidated by determination of the enzyme activities in the pressjuice of the intact muscle tissue. In the muscles of the different species positive correlations between myoglobin content and the activities of the three enzymes were found, which were closer for pigs and chicken than for cattle and ducks. At least 90 percent of the total activity of LIPDH, CS and HADH was located in the mitochondria.
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PMID:[Lipoamide dehydrogenase, citrate synthase and beta-hydroxyacyl-CoA-dehydrogenase of skeletal muscle. III. Activity and subcellular distribution in light and dark musculature of cattle, swine and poultry]. 654 97

Myoglobin, muscle fibre diameter, and citrate synthase activity were measured in leg muscle of untrained and trained men and in the myocardium from the apex of the left ventricle and from papillary muscle in patients subjected to open heart surgery. The citrate synthase (CS) activity was 60% higher in trained than in untrained skeletal muscle. In the myocardium it was around four times greater than in untrained skeletal muscle but there was no difference between the apex of the left ventricle and papillary muscle. The fibre diameter varied almost threefold between the different groups of muscles with the largest diameter in untrained skeletal muscle and the with the largest diameter in untrained skeletal muscle and the smallest in papillary muscle. The myoglobin content in trained skeletal muscle did not differ from that of untrained muscle. In the left ventricle it was only 40% of that found in untrained muscle while papillary muscle had almost twice as high a myoglobin content as did the left ventricle. The ratio between myoglobin and fibre diameter, however, was of similar magnitude in skeletal muscle and the left ventricle while it was twice as high in papillary muscle as in the other muscles. In conclusion, the diffusion distance in terms of fibre diameter decreased with increased oxidative capacity (CS activity), when comparing the statistical means of the four different groups. The capacity for oxygen diffusion in relation to oxygen demand measured as the ratio of myoglobin to fibre diameter appeared to be of similar magnitude in skeletal muscle and left ventricle but was higher in papillary muscle.
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PMID:Myoglobin content in human skeletal muscle and myocardium: relation to fibre size and oxidative capacity. 674 65

Male rats were either sham-operated (N) or castrated (C) at 65 days of age. They were further subdivided into sedentary or exercise groups that were trained by treadmill running 5 days/wk for 12 wk. During the last 10 days of training, the animals received daily subcutaneous injections of cortisone acetate (CA) (100 mg/kg) or 1% carboxymethylcellulose. Body weight decreased approximately 25% in all groups that received CA. The fast-twitch plantaris and gastrocnemius muscle weights were approximately 35% lower in CA-treated versus cortisone-free N and C sedentary animals. Exercise prevented from one-fourth to one-half of the muscle weight loss in N and C runners when compared to their respective pair weight controls. Muscle weights of the CA-treated freely eating N controls were significantly less than that of N runners that received CA. In plantaris muscles of both N and C animals that received CA, total protein concentration and citrate synthase activity, a mitochondrial marker, remained constant, but their amounts per muscle decreased in proportion to the atrophy. However, myoglobin concentration increased in plantaris muscles of CA-treated animals, although total myoglobin per muscle was reduced slightly. Myoglobin levels were increased in plantaris muscles both as a result of training and CA, but citrate synthase activity was increased only as a result of the exercise. These results show that exercise can retard the glucocorticoid-induced muscle atrophy.
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PMID:Partial prevention of glucocorticoid-induced muscle atrophy by endurance training. 728 23

The effects of electrically induced dynamic muscle contractions on muscle endurance, strength, morphology and enzymatic adaptation were studied in seven male physical education students. The training program consisted of electrically induced one-leg extensions on a modified Krogh cycle with a 30-Watt (W) load for 60 min, 3 times a week for 4 weeks. Muscle fiber type composition was unchanged, but diffusional capacity was increased after electromyostimulation training. The endurance capacity in the trained leg increased by 82% (p < 0.01), but there were no significant changes in citrate synthase, phosphofructokinase activities, and carbonic anhydrase III and myoglobin contents, suggesting that neural adaptation and learning were more important factors for the increased endurance capacity than enzymatic adaptation. Prolyl 4-hydroxylase activity, a marker of collagen biosynthesis, increased 3-fold (p < 0.01) as a result of the training. This could be due to muscle damage caused by electrically induced muscle contractions. In conclusion, electrically induced dynamic muscle contractions can increase muscle endurance without clear concominant changes in muscle morphologic and enzymatic adaptation. Increased prolyl 4-hydroxylase activity could suggest muscle damage caused by electrically induced muscle contractions.
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PMID:Training effects of electrically induced dynamic contractions in human quadriceps muscle. 766 36


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