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)

Single canine Purkinje cells were isolated by microdissection and analyzed quantitatively for six enzymes of energy metabolism. Subendocardial Purkinje cells were clearly distinguishable morphologically and biochemically from adjacent myocardium and had enzyme levels comparable with extramural Purkinje cells. Oxidative enzymes, citrate synthase, malate dehydrogenase, and beta-hydroxyacyl CoA dehydrogenase were 40-60% lower in Purkinje cells than in myocardium. Lactate dehydrogenase was also 40% lower, but the other glycolytic enzymes, hexokinase and phosphofructokinase, were similar in level in myocardium and Purkinje cells. The results of this study show that it is completely practicable to apply quantitative histochemical analysis to biochemical study of the cardiac conducting system.
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PMID:Quantitative histochemistry of canine cardiac Purkinje fibers. 622 55

Adult female rats were subjected to an eleven-week endurance-training programme, and, for the first time, the maximum activities of enzymes that can indicate the quantitative capacities of both anaerobic glycolysis and the Krebs cycle in muscle (viz. 6-phosphofructokinase and oxoglutarate dehydrogenase respectively) were measured in heart plus white and fast-oxidative skeletal muscle. No changes were observed in heart muscle. In fast-oxidative skeletal muscle, activities of hexokinase, citrate synthase, and oxoglutarate dehydrogenase were increased by 51, 26, and 33% respectively but there was no effect on 6-phosphofructokinase. These results demonstrate that in red muscle there is no effect of this training programme on the anaerobic capacity but that of the aerobic system is increased by one third. In white skeletal muscle, only the activity of citrate synthase was increased, which indicates that this activity may not provide even qualitative information about changes in capacity of the Krebs cycle.
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PMID:The effect of endurance-training on the maximum activities of hexokinase, 6-phosphofructokinase, citrate synthase, and oxoglutarate dehydrogenase in red and white muscles of the rat. 622 45

The distributions of glycogen phosphorylase, hexokinase, phosphofructokinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, citrate synthase, malate dehydrogenase, beta-hydroxyacyl CoA dehydrogenase, and adenylokinase were determined in the mudpuppy retina. Distinct differences were found in regard to the glycolytic and oxidative capacities of the various layers. In the outer retina, citric acid cycle enzymes were high while glycolytic enzymes were low. Synaptic zones were distinctly enriched in all energy-producing enzymes. Mudpuppy photoreceptors were found to be rich in phosphorylase but poor in glucose-6-phosphate dehydrogenase, suggestive of some evolutionary divergence from mammals in the metabolic machinery which is used to support the visual process.
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PMID:Enzymes of energy metabolism in the mudpuppy retina. 623 83

Peripheral adaptations to 3 months of physical endurance training without food restrictions were studied in skeletal muscles of 14, middle-aged, physically untrained, obese women. In comparison to aged-matched controls of normal weight, the obese group showed significantly lower isometric endurance. In the obese group, physical training resulted in a significant increase of maximal isometric and isokinetic strength. Isokinetic but not isometric endurance also increased after training. The isometric strength of obese women showed a positive correlation with the percentage of FTb fibres. The training (50 min/day, 3 days/w) did not result in any change in body weight, body fat, and the number and weight of fat cells. The 20% increase of VO2 max after training was found to be significantly correlated with the increase in the number of capillaries around muscle fibres. The relative percentage of FTa fibres, the number of capillaries per fibre as well as the activities of citrate synthase, 3-hydroxy-acyl-CoA-dehydrogenase, and hexokinase showed a significant increase after training. The concentrations of glucose during OGTT showed a trend to decrease with a significant decrease at the end glucose curve (120-min value). The concentration of insulin and C peptide and the insulin removal did not change after training. The changes in the concentration of glucose during OGTT was significantly correlated with the increase in muscle capillarization and of dynamic endurance.
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PMID:Physical training in obese women. Effects of muscle morphology, biochemistry and function. 638 Oct 44

To evaluate the relationships between changes in muscle morphology and metabolic adaptation to physical training in obesity, twenty obese women were subjected to a physical training programme with three sessions a week for 3 months. Physical training resulted in lowering of plasma insulin and improved glucose tolerance. Neither body weight nor body fat changed. With physical training the percentage distribution of fast twitch oxidative (FTa) muscle fibres (m vastus lateralis) increased (from 30.3 +/- 5.1% to 35.2 +/- 4.8%, P less than 0.05) and that of fast twitch glycolytic fibres decreased (from 18.3 +/- 6.6 to 5.8 +/- 4.8%, P less than 0.05). The number of capillaries increased, mainly around slow twitch (ST) fibres (from 4.5 +/- 0.6 to 5.8 +/- 0.8, P less than 0.01) and fast twitch oxidative (FTa) fibres (from 3.9 +/- 0.7 to 4.7 +/- 0.8, P less than 0.01). The activities of oxidative enzymes (cytochrome-c-oxidase and citrate synthase) increased (P less than 0.05) while those of glycolytic enzymes (phosphofructokinase and hexokinase) decreased after physical training (P less than 0.01). Significant negative correlations between plasma insulin and number of capillaries in contact with ST fibres (r = 0.80, P less than 0.001) and FTa fibres (r = 0.62, P less than 0.001) were found before training. The capillary density around those fibres could predict 80% of the explained variance of plasma insulin levels (P less than 0.001). The changes of glucose concentration after training could be predicted by observed changes in enzyme activities. The strong associations between muscle morphology and capillarization and enzyme activities and glucose and insulin concentrations and their changes after training suggest an important regulatory role of muscle which warrants further studies.
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PMID:Relationship between muscle morphology and metabolism in obese women: the effects of long-term physical training. 640 24

The activities of hexokinase (HK), lactate dehydrogenase (LDH), citrate synthase (CS) and 3-hydroxyacyl-CoA-dehydrogenase (HAD) were measured in the costal diaphragm (DI) and in the latissimus dorsi (LD), a non respiratory muscle, of 21 middle aged men: 10 normal subjects and 11 patients with moderate chronic obstructive pulmonary disease (COPD). In the normal subjects, all the enzymatic activities were significantly higher in the diaphragm (p less than 0.01) than in the latissimus dorsi, the mean increase ranging from 61 to 118%. Chronic obstructive pulmonary disease failed to cause any further increase in enzymatic activities in the DI; on the contrary, a significant decrease of HK and LDH (30%, p less than 0.01) was observed. Enzymatic activities of LD were unaffected by COPD. These data show that the metabolic enzymatic activities in the diaphragm of normal middle aged subjects is similar to that of the vastus lateralis of highly trained young athletes, suggesting that DI is a highly trained muscle in normal man.
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PMID:Metabolic enzymatic activities in the diaphragm of normal men and patients with moderate chronic obstructive pulmonary disease. 644 Jun 9

1. In rat kidney cortex, outer and inner medulla the development of activities of seven enzymes was investigated during postnatal ontogeny (10, 20, 30, 60 and 90 days of age). The enzymes were selected in such a manner, as to characterize most of the main metabolic pathways of energy supplying metabolism: hexokinase (glucose phosphorylation, HK), glycerol-3-phosphate dehydrogenase (glycerolphosphate metabolism or shunt, GPDH), triose phosphate dehydrogenase (glycolytic carbohydrate breakdown, TPDH), lactate dehydrogenase (lactate metabolism, LDH), citrate synthase (tricarboxylic acid cycle, aerobic metabolism, CS), malate NAD dehydrogenase (tricarboxylic acid cycle, intra-extra mitochondrial hydrogen transport, MDH) and 3-hydroxyacyl-CoA-dehydrogenase (fatty acid catabolism, HOADH). 2. The renal cortex already differs metabolically from the medullar structures on the 10th day of life. It displays a high activity of aerobic breakdown of both fatty acids and carbohydrates. Its metabolic capacity further increases up to the 30th day of life. 3. The outer medullar structure is not grossly different from the inner medulla on the 10th day of life. Further it differentiates into a highly aerobic tissue mainly able to utilize carbohydrates. It can, however, to some extent, also utilize fatty acids aerobically and produce lactate from carbohydrates anaerobically. 4. The inner medullar structure is best equipped to utilize carbohydrates by anaerobic glycolysis, forming lactate. This feature is already pronounced on the 10th day of life, its capacity increases to some extent during postnatal development, being highest between the 10th and the 60th day of life.
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PMID:Postnatal changes of some enzymatic activities of energy supplying metabolism in the cortex, inner and outer medulla of the rat kidney. 644 14

Skeletal limb muscles of the dog could generally be differentiated into three fibre types according to myosin adenosine triphosphatase (ATPase) (pH 9.4) and succinic dehydrogenase activities. However, because this was not always possible, for comparative purposes only, division into low myosin ATPase (slow twitch) type I and high myosin ATPase (fast twitch) type II fibres was used. The percentage of these fibre types in m deltoideus, m triceps brachii caput longum, m vastus lateralis, m gluteus medius, m biceps femoris and m semitendinosus was examined in the greyhound, crossbred and foxhound. In all muscles the greyhound had a significantly higher percentage of fibres with high myosin ATPase activity at pH 9.4 than the other breeds, with almost 100 per cent in most muscles examined. The activities of nine enzymes and glycogen concentration were determined in m gluteus medius and m semitendinosus of the greyhound and crossbred. Significantly higher levels of creatine kinase, aldolase, alanine aminotransferase and citrate synthase and significantly lower activities of 3-hydroxyacyl coenzyme A dehydrogenase and hexokinase were found in both muscles of the greyhound. The implications of these findings are discussed.
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PMID:Skeletal muscle fibre composition in the dog and its relationship to athletic ability. 645 29

The regional enzyme activities of glucose metabolism in the rat brain were investigated. Hexokinase (EC 2.7.1.1) and pyruvate dehydrogenase (EC 1.2.4.1), key enzymes for glucose metabolism, showed no changes in activity in all the regions studied of the aging brain as compared with the adult brain. However, the activity of D-3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) is low throughout the adult brain and, in contrast with hexokinase and pyruvate dehydrogenase, its activity decreases significantly during aging. Other enzymes that showed significant decreases during aging are aldolase (EC 4.1.2.13), lactate dehydrogenase (EC 1.1.1.27), citrate synthase (EC 4.1.3.7), and NAD+-linked isocitrate dehydrogenase (EC 1.1.1.41). The catabolic enzyme in cholinergic metabolism, acetylcholinesterase (EC 3.1.1.7), selected as an example of a non-energy-metabolising enzyme, also showed significant decreases in all regions of the brain in aging, although its highest activity remained in the striatum. These results are discussed with respect to the energy metabolism in various brain regions and their status with aging.
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PMID:Energy-metabolizing enzymes in brain regions of adult and aging rats. 646 Aug 51

Long-term electrical stimulation (14-28 days) of rabbit fast muscles (tibialis anterior, TA and extensor digitorum longus, EDL) using intermittent high frequency (3 trains per min of 5 s duration at 40 Hz, for 8 h per day) produced changes in enzyme activities similar to those found with continuous stimulation at a frequency occurring in nerves to slow muscles (10 Hz). The activity of citrate synthetase, 3-hydroxyacyl-CoA dehydrogenase and succinate dehydrogenase increased two to 3-fold within 28 days. There was a 4-fold increase in hexokinase whereas phosphofructokinase, pyruvate kinase, lactate dehydrogenase and fructose-1,6-diphosphatase decreased to about 60% of the activity levels in the contralateral unstimulated muscles. Blood flow and oxygen consumption at rest were not changed even after 28 days of stimulation, but were increased during contractions in muscles stimulated at either frequency, the level being twice as high as in control muscles. Glucose uptake was similar to that in control muscles both at rest and during contractions and the output of lactate was similar to that found in control muscles in muscles stimulated at 40 Hz. Muscles stimulated at 10 Hz had smaller lactate output. Thus intermittent stimulation at high frequency (40 Hz) and continuous low frequency (10 Hz) produced similar changes in aerobic metabolism and fuel uptake provided that the total number of stimuli was comparable and that the stimulation was carried out for sufficiently long period.
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PMID:Effects of different patterns of long-term stimulation on blood flow, fuel uptake and enzyme activities in rabbit fast skeletal muscles. 652 41


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