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)

Fibre characteristics and enzyme activities were determined for the gluteus, semitendinosus, vastus lateralis and triceps brachii muscles of 55 Standardbred trotters of different ages. Four fibre types (I, IIA, IIB, IIC) were demonstrated by histochemical staining of myofibrillar adenosine triphosphatase after preincubation at different pH values. Type II fibres predominated in all the muscles and the type IIA/IIB ratio was higher in horses over 5 years than in younger horses, except in the vastus in which the IIA/IIB ratio did not change with age. The vastus had the highest proportion of type IIA fibres and the semitendinosus the highest proportion of type IIB fibres. Histochemical demonstration of NADH dehydrogenase disclosed that almost 100 per cent of the type IIA and many of the type I and IIB fibres were medium-stained; the remaining type I fibres were darkly stained and the type IIB fibres lightly stained. In older horses more fibres were stained for NADH dehydrogenase. The activity of triosephosphate dehydrogenase decreased that that of 3-hydroxy-acyl-coA dehydrogenase and citrate synthase increased in all the muscles except the vastus with increasing age. The greatest increase in oxidative capacity occurred in the gluteus and triceps. Training, rather than age, was regarded as the factor inducing these changes. The results emphasise that histochemical data are only semiquantitative, and there are apparent discrepancies in the intensities of histochemical staining and the biochemical evaluation of various enzymes.
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PMID:Histochemical properties of muscle fibres types and enzyme activities in skeletal muscles of Standardbred trotters of different ages. 644 65

Lizard skeletal muscle fiber types were investigated in the iliofibularis (IF) muscle of the desert iguana (Dipsosaurus dorsalis). Three fiber types were identified based on histochemical staining for myosin ATPase (mATPase), succinic dehydrogenase (SDH), and alphaglycerophosphate dehydrogenase (alphaGPDH) activity. The pale region of the IF contains exclusively fast-twitch-glycolytic (FG) fibers, which stain dark for mATPase and alphaGPDH, light SDH. The red region of the IF contains fast-twitch-oxidative-glycolytic (FOG) fibers, which stain dark for all three enzymes, and tonic fibers, which stain light for mATPase, dark for SDH, and moderate for alphaGPDH. Enzymatic activities of myofibrillar ATPase, citrate synthase, and alphaGPDH confirm these histochemical interpretations. Lizard FG and FOG fibers possess twitch contraction times and resistance to fatigue comparable to analogous fibers in mammals, but are one-half as oxidative and several times as glycolytic as analogous fibers in rats. Lizard tonic fibers demonstrate the acetylcholine sensitivity common to other vertebrate tonic fibers.
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PMID:Histochemical, enzymatic, and contractile properties of skeletal muscle fibers in the lizard Dipsosaurus dorsalis. 645 26

A mathematical model is proposed to describe the interaction between glycolysis, the Krebs cycle and 3-oxidation (beta OX). The model incorporates the activations of phosphofructokinase by AMP and of isocitrate dehydrogenase by ADP as well as the inhibitions of citrate synthase by citrate, of acyl CoA synthase by excess CoAsAcyl, of pyruvate dehydrogenase (PDH) and the beta OX helix by the products CoAsAc and NADH. These regulations have been shown to provide consecutive triggering of the fatty acid and glucose oxidation systems with an increase in the ATPase load, the beta OX of fatty acids being a major source of energy at small loads. The steady state rates of glycolysis and PDH-reaction begin to increase at larger loads when the rate of beta OX is close to its maximum value. At maximum ATPase loads, the glucose oxidation accounts for more than 80% of the total energy production. Under limited fatty acid supply, the transfer to glucose oxidation gives rise to a region of the ATPase loads, where in the steady state levels of NADH and CoAsAc increase with load.
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PMID:[Ratio between carbohydrate and lipid metabolism in muscle cell energy metabolism during ATPase loading. Mathematical model]. 645 74

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

This study was undertaken to examine the effects of thyroid hormonal deficiency on (1) standard (SMR) and maximal (VO2max) rates of O2 consumption, (2) tissue glycolytic and oxidative capacities and (3) submaximal locomotory endurance in a lizard (Dipsosaurus dorsalis). Surgical thyroidectomy induced hypothyroidism in all animals as determined by levels of plasma thyroxine. Hypothyroid lizards had lower levels of SMR (-48%), VO2max (-16%) and citrate synthase activity in liver, heart and skeletal muscle compared to controls. There was a correlated decrease in locomotory endurance in thyroid-deficient animals. Pyruvate kinase activity (an index of glycolytic capacity) in all tissues, and myofibrillar ATPase activity (an index of contractile velocity) in white iliofibularis muscle, showed no significant changes in thyroid-deficient animals. Thyroid hormones appear to be important in ultimately establishing an animal's capacity for locomotory endurance. These findings suggest a new selective context for understanding the evolution of thyroid function.
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PMID:Reduced aerobic capacity and locomotory endurance in thyroid-deficient lizards. 673 62

Chronic indirect stimulation (10 Hz) was performed on rabbit tibialis anterior muscle. Long-term stimulation (52-140 days) produced a transformation of the fast tibialis anterior into a slow red muscle as judged from the histochemistry of myofibrillar actomyosin ATPase, the pattern of myosin light chains and the thorough rearrangement of the enzyme activity pattern of energy metabolism. Activity levels of citrate synthetase (CS), malate dehydrogenase (MDH), succinate dehydrogenase (SDH), 3-hydroxy-acyl-CoA dehydrogenase (HAD), and lactate dehydrogenase (LDH) were determined quantitatively by either microbiochemical assays (CS, MDH, HAD and LDH) on microdissected, single fibres or by kinetic microphotometry on cross-sectioned fibres (SDH). The activity profiles of these enzymes displayed pronounced scattering in the fibre population of the unstimulated muscle. Despite a several fold increase in the activities of CS, MDH, SDH and HAD and a pronounced decrease in LDH, chronic stimulation failed to abolish the metabolic heterogeneity of the fibre population. It is possible that chronic indirect stimulation cannot produce uniformity of fibres because of continuing diverse natural activity of the motor units.
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PMID:Effects of chronic stimulation on the metabolic heterogeneity of the fibre population in rabbit tibialis anterior muscle. 674 46

Anaerobic threshold (AT) and maximum oxygen uptake (max VO2) were determined in 15 young female cross-country skiers, aged 15--20 years, during incremental bycycle ergometer exercise. Succinate dehydrogenase (SDH), malate dehydrogenase (MDH), citrate synthase (CS) and lactate dehydrogenase (LDH) were analyzed biochemically and percentage of slow twitch fibres (%ST fibres, myosin adenosine triphosphatase staining) histochemically in muscle samples obtained from m. vastus lateralis. Max VO2 correlated significantly with anaerobic threshold in ml x kg-1 x min-1 (mlAT) but when AT was expressed in percent of max VO2 (%AT) the correlation was insignificant. Significant correlations were found between %AT and SDH (r = 0.63) and between mlAT and CS (r = 0.58). Max VO2 showed no significant correlations with the enzymes studied or %ST fibres. The results of the study seem to support the hypothesis that anaerobic threshold is related to oxidative capacity of muscle.
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PMID:Anaerobic threshold, skeletal muscle enzymes and fiber composition in young female cross-country skiers. 737 21

Muscle cell fiber types in gracilis, rectus femoris, and long head of triceps brachii muscles of ferrets and dogs were identified on serial sections stained for myosin ATPase after preincubation at pH values of 9.8, 4.6, and 4.3 and for NADH-tetrazolium reductase (NADH-TR) activity. Although fiber types I and II were identified, the ATPase stain did not demonstrate classic type IIA/IIB fiber differences in either species. However, two type II fiber subtypes could be distinguished in the ferret because they differed slightly in staining intensity with ATPase at pH 4.3 and markedly with NADH-TR. One ferret type II fiber (designated II dark or IID) was smaller, slightly darker on ATPase, more oxidative on NADH-TR, and comprised more muscle volume than the other type II fiber (designated II light IIL). The IID fibers of ferret may represent the IID/X fibers of other authors. Both ferret type II fiber subtypes stained darker at pH 4.3 than canine II fibers. The NADH-TR staining indicated high oxidative activity in canine and ferret type I fibers. In contrast, type II fibers in the dog and IIL fibers in the ferret were moderately oxidative. Canine type IIC fibers were intermediate between type I and type II, whereas in the ferret, type IIC fibers were highly oxidative, as were type IID fibers. Ferret muscles are more oxidative than canine muscles according to NADH-TR staining. Also, ferret muscles possess 40-100% higher citrate synthase activity as compared to canine muscles.
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PMID:Comparison of muscle cell fiber types and oxidative capacity in gracilis, rectus femoris, and triceps brachii muscles in the ferret (Mustela putorius furo) and the domestic dog (Canis familiaris). 769 Oct 36

The activities of three mitochondrial oxidative enzymes (citrate synthase, 3-ketoacid-CoA transferase, beta-hydroxyacyl-CoA dehydrogenase) and Na-K-ATPase were microassayed in isolated segments of the rat proximal convoluted tubule (PCT) and medullary thick ascending limb of the loop of Henle (mTAL). The effects of adrenalectomy (ADX) and ADX plus exogenous glucocorticoids were analyzed. The hormonal replacement was daily injections of dexamethasone (10 micrograms/100 g body weight/24 h) for 5 days. ADX lowered the activity of all oxidative enzymes studies in the mTAL, but not in the PCT and led to a decrease in Na-K-ATPase in both nephron segments. Dexamethasone restored the normal level of oxidative enzymes and Na-K-ATPase in the mTAL and of Na-K-ATPase in the PCT. We conclude that the activities of citrate synthase, 3-ketoacid-CoA transferase and beta-hydroxyacyl-CoA dehydrogenase and of Na-K-ATPase are coordinately regulated in the mTAL and that glucocorticoids are essential for the long-term regulation of these enzyme activities in this nephron segment. In contrast, the activities of mitochondrial oxidative enzymes are not influenced by glucocorticoids in the PCT. This study presents the first evidence for a cell-specific regulation by glucocorticoids of oxidative metabolism in the nephron of adult rat kidney.
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PMID:Effect of glucocorticoids on mitochondrial oxidative enzyme and Na-K-ATPase activities in the rat proximal tubule and thick ascending limb of Henle. 769 38

Samples were taken at slaughter from heart and both locomotor and nonlocomotor muscles from animals of similar body weight but adapted to different levels of activity: three horses and three steers. All samples were analyzed biochemically to measure the activity of key metabolic enzymes. The skeletal muscles were analyzed histochemically for fibre type composition, fibre area and capillary supply. The general pattern of differences in fibre type composition and metabolic profile between muscle groups was similar in both horses and steers. The hearts of both species had high citrate synthase (CS), 3-OH-acylCoA-dehydrogenase (HAD) and hexokinase (HK) and low lactate dehydrogenase (LDH) activities. In both species, deep portions of muscles and muscles localized deeper in the body had a more oxidative metabolic profile than superficial portions and muscles. Taking all muscles into account, it was found that CS and HAD were higher and LDH lower in horse than in steer muscles. Horse muscles contained more type IIA fibres and had a higher capillary supply than steer muscles. There was no difference between the two species regarding mean fibre area. The adaptation of the horse to a higher level of activity in comparison with steers was reflected in a higher oxidative capacity, better vascularization and a larger proportion of type IIA fibres. It was also obvious from these results that the ATPase fibre-typing system does not reflect the metabolic profile of a muscle.
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PMID:Fibre type distribution, capillarization and enzymatic profile of locomotor and nonlocomotor muscles of horses and steers. 770 35


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