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)

The histochemical, biochemical, and electrophysiological properties of selected muscles were evaluated in spontaneously hypertensive rats (SHR) and compared with their normotensive Wistar-Kyoto (WKY) counterparts. As early as 4 wk of age, slow muscles (soleus) of SHR displayed a significant alteration in fiber type distribution with a decrease of slow-twitch fibers (from 64 to 53%) and a simultaneous increase of type IIA-fibers (from 19 to 39%). In addition, soleus from young SHR had a significant enhancement of both oxidative (citrate synthase, 3-hydroxyacyl-CoA dehydrogenase) and glycolytic [lactate dehydrogenase (LDH)] capacities, which could be partly related to a capillary rarefaction. During development (from the 4th to the 12-14th wk), in the soleus muscle the histochemical differences between SHR and WKY were amplified, whereas most of the enzymatic differences between strains were abolished, except for a significantly higher LDH activity. These histochemical changes had only marginal repercussions on soleus electrophysiological properties. SHR animals had a significantly higher basal metabolic rate, which could not be accounted for by elevation of thyroid hormones. The origin of the slow-to-fast fiber type transition in slow muscle remains unclear but could be related to the increased level of plasma catecholamines in SHR. Indeed, chronic treatment of rats with a beta 2-receptor agonist has been reported to cause slow-to-fast muscle fiber transition [R. J. Zeman, R. Ludemann, T. G. Easton, and J. D. Etlinger. Am. J. Physiol. 254 (Endocrinol. Metab. 17): E726-E732, 1988].
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PMID:Evidence of a slow-to-fast fiber type transition in skeletal muscle from spontaneously hypertensive rats. 230 28

The purpose of this study was to investigate metabolic changes in equine muscle from birth to 1 yr of age. Duplicate biopsies from the middle portion of the gluteus medius were obtained from a depth of 2 cm beneath the superficial fascia at 1 day, 7 days, 1 mo, 3 mo, 6 mo, and 1 yr of age in 11 quarter horses and at 1 day, 3 mo, 6 mo, and 1 yr of age in 5 Standardbreds. Muscle enzyme activities determined were citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, phosphorylase, and lactate dehydrogenase. Percent fast-twitch, fast-twitch high oxidative, and slow-twitch oxidative fiber types were determined using succinate dehydrogenase and myosin adenosinetriphosphatase (pH 9.4) histochemical stains. Histochemically determined muscle fiber-type percents did not change dramatically with increasing age. However, lactate dehydrogenase activity increased threefold in quarter horses and twofold in Standardbreds, and phosphorylase activity increased sixfold in quarter horses and sevenfold in Standardbreds from 1 day to 6 mo of age. Citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities decreased during the first 3 mo of age in quarter horses.
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PMID:Changes in the metabolic profile of equine muscle from birth through 1 yr of age. 234 82

To study the metabolic and functional changes that occur during training with inspiratory flow resistive loads, a chronically instrumented unanesthetized sheep preparation was used. Sheep were exposed to resistances ranging from 50 to 100 cmH2O.l-1.s, for 2-4 h/day, 5-6 days/wk, for a total of 3 wk. Load intensity was adjusted to maintain arterial Po2 (PaO2) above 60 Torr and arterial PCO2 (PaCO2) below 45 Torr. Training produced significant (P less than 0.05) increases in citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, and cytochrome oxidase in the costal and crural diaphragm of the trained sheep (n = 9) compared with control sheep (n = 7). Phosphofructokinase did not increase. In the quadriceps, citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, and phosphofructokinase did not change with training but cytochrome oxidase increased significantly (P less than 0.01). Function of the diaphragm was assessed in a subset of five sheep exposed to the same severe load 1 wk before and 2 days after the final training session. After training, sheep had a lower PaCO2 (10-40%), generated a higher transdiaphragmatic pressure (20-40%), and could sustain this level of transdiaphragmatic pressure for 0.5-2 h longer. The respiratory duty cycle was 10-15% lower, whereas minute ventilation and tidal volume were 20-30% higher in the posttraining test. We conclude that 1) training with inspiratory flow resistive loads improves the performance of the respiratory neuromuscular system and 2) the shift in enzyme profile of the diaphragm is at least in part responsible for this improvement.
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PMID:Metabolic and functional adaptation of the diaphragm to training with resistive loads. 254 Jan 38

1. The activities of phosphofructokinase (PFK), citrate synthetase (CS), lactate dehydrogenase (LDH), 3-hydroxyacyl-CoA dehydrogenase (ACDH) and cytochrome-c oxidase(Cyt-ox) in the calf muscle tissue were compared in subjects with intermittent claudication (n = 38) and controls (n = 20). The activities of CS, ACDH and Cyt-ox were increased and the activity of Cytox was positively correlated to the maximal walking distance (MWD) in the patients. 2. Thirty-three patients with intermittent claudication were randomized to three treatment groups: (1) operative surgery, (2) operative surgery supplemented with physical training and (3) physical training alone. Before and after 6-12 months of treatment, symptom-free walking distance (SFWD), MWD, ankle-brachial blood pressure quotient (ankle index), maximal plethysmographic calf blood flow (MPBF) and the activities of PFK, CS, LDH, ACDH and Cyt-ox were measured. 3. SFWD and MWD increased in all three groups. Ankle index and MPBF increased in groups 1 and 2, but were unchanged in group 3. The activities of Cyt-ox and CS decreased with operation, but the activity of Cyt-ox was further augmented with training in group 3. Overall, the change in ankle index explained 80-90% of the variability in walking performance. In a separate analysis, the increased activity of Cyt-ox in group 3 was positively correlated to, and explained 31% of the variability in, the improvement in SFWD. 4. These findings indicate that both physical activity and a reduced calf blood flow are necessary conditions for the enzymatic adaptation to take place. A causal relationship between metabolic adaptation in the muscle tissue and walking performance is suggested.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Muscle enzyme adaptation in patients with peripheral arterial insufficiency: spontaneous adaptation, effect of different treatments and consequences on walking performance. 255 5

Substrate preferences of isolated mitochondria and maximal enzyme activities were used to assess the oxidative capacities of red muscle (RM) and white muscle (WM) of carp (Cyprinus carpio). A 14-fold higher activity of citrate synthase (CS) in RM reflects the higher mitochondrial density in this tissue. RM mitochondria oxidize pyruvate and fatty acyl carnitines (8:O, 12:O, 16:O) at similarly high rates. WM mitochondria oxidize these fatty acyl carnitines at 35-70% the rate of pyruvate, depending on chain length. WM has only half the carnitine palmitoyl transferase/CS ratio of RM, but similar ratios of beta-hydroxyacyl CoA dehydrogenase/CS. Ketone bodies are poor substrates for mitochondria from both tissues. In both tissues mitochondrial alpha-glycerophosphate oxidation was minimal, and alpha-glycerophosphate dehydrogenase was present at low activities, suggesting the alpha-glycerophosphate shuttle is of minor significance in maintaining cytosolic redox balance in either tissue. The mitochondrial oxidation rates of other substrates relative to pyruvate are as follows: alpha-ketoglutarate 90% (RM and WM); glutamate 45% (WM) and 70% (RM); proline 20% (WM) and 45% (RM). Oxidation of neutral amino acids (serine, glycine, alanine, beta-alanine) was not consistently detectable. These data suggest that RM and WM differ in mitochondrial properties as well as mitochondrial abundance. Whereas RM mitochondria appear to be able to utilize a wide range of metabolic fuels (fatty acids, pyruvate, amino acids but not ketone bodies), WM mitochondria appear to be specialized to use pyruvate.
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PMID:Oxidative properties of carp red and white muscle. 273 62

Selected biochemical parameters of the ventricular myocardium were compared among several orders of adult mammals with established differences in resting heart rate (cattle, 51 beats/min; swine, 68; canine, 107; rabbit, 256; guinea-pig, 273; rat, 355; mouse, 475). It was hypothesized that the biochemical character of mammalian myocardia is associated with the chronic functional demand on the muscle. Therefore, differences observed in the myocardial biochemical potential among the species could reflect differences in resting heart rate. Myocardia from smaller mammals with higher resting heart rate had significantly (P less than 0.05) higher maximal activities of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, lactate dehydrogenase (muscle/total), hexokinase and oxidation rates of glucose and palmitate than did larger mammals with lower resting heart rate. Maximal activities of phosphorylase and phosphofructokinase were more uniform across the animals. Correlation coefficients determined among average values of measured biochemical parameters and resting heart rate indicated that resting heart rate was closely associated with: citrate synthase (r = 0.86), 3-hydroxyacyl-CoA dehydrogenase (r = 0.93), ratio muscle/total lactate dehydrogenase (r = 0.89), hexokinase (r = 0.89), glucose oxidation (r = 0.88), and palmitate oxidation (r = 0.93). Significant correlations were observed among all of these parameters with the exception of citrate synthase vs. 3-hydroxyacyl-CoA dehydrogenase, and glucose oxidation vs. muscle/total lactate dehydrogenase. It was concluded that the oxidative capacity of mammalian myocardia was closely associated with resting heart rate, whereas the glycolytic potential of the myocardia was more uniform among the species.
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PMID:Biochemical characteristics of mammalian myocardia. 274 58

1. The effect of hypocaloric feeding (25% of normal food intake for 21 days) of rats on the enzymic and metabolic adaptations in the gastrocnemius, plantaris and soleus muscles was studied. 2. In control and hypocaloric rats the muscle relaxation rates at 100 Hz were 35.76 and 11.38% force loss/10 ms respectively. Control rats exhibited enhanced force of muscle contraction as the frequency of stimulation increased from 10 to 100 Hz, with maximum force being at 100 Hz. Hypocaloric rats exhibited a decrease in the increment of force being exerted at high frequencies, with maintenance of force at lower stimulatory frequencies. 3. In muscles of hypocaloric rats, there were significant decreases in the maximal activities of hexokinase (17.6-37.0%), 6-phosphofructokinase (22.7-34.2%), pyruvate kinase (21.2-36.0%), citrate synthase (34.1-41.5%), oxoglutarate dehydrogenase (29.4-52.4%) and 3-hydroxyacyl-CoA dehydrogenase (26.7-32.1%), whereas the activities of glycogen phosphorylase increased (23.8-43.4%) compared with control values. 4. In soleus-muscle strip preparations of hypocaloric rats, there were significant decreases in the rates of lactate production (28.1%) and glucose oxidation (32.6%) compared with control preparations. 5. Mitochondrial preparations from muscles of hypocaloric rats incubated with various substrates exhibited decreased rates of oxygen uptake compared with control preparations. 6. In muscles of hypocaloric rats (gastrocnemius and soleus), there were significant decreases in the concentrations of glycogen (P less than 0.001) and phosphocreatine (P less than 0.001) and increases in those of pyruvate (P less than 0.001), lactate (P less than 0.001) and ADP (P less than 0.001), whereas those of ATP and AMP remained unchanged. 7. Calculated [lactate]/[pyruvate] and [ATP]/[ADP] ratios exhibited significant increases (P less than 0.05) and decreases (P less than 0.05) in muscles of hypocaloric rats respectively. 8. The results are discussed in relation to the genesis of muscle dysfunction caused by malnutrition.
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PMID:Enzymic and metabolic adaptations in the gastrocnemius, plantaris and soleus muscles of hypocaloric rats. 277 8

Patients with heart failure frequently exhibit abnormal skeletal muscle metabolic responses to exercise, as assessed with 31P NMR. To investigate whether these metabolic abnormalities are due to intrinsic skeletal muscle changes, we performed gastrocnemius muscle biopsies on 22 patients with heart failure (peak VO2, 15.4 +/- 4.7 ml/kg/min; ejection fraction, 20 +/- 7%) and on eight normal subjects. Biopsies were analyzed for fiber type and area, capillarity, citrate synthase, phosphofructokinase, lactate dehydrogenase, and beta-hydroxyacyl CoA dehydrogenase activity. All patients with heart failure also underwent 31P NMR studies of their calf muscle during plantarflexion at three workloads. Muscle pH responses and the relation of the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) to systemic VO2 were then evaluated. Compared with normal subjects, patients with heart failure exhibited a shift in fiber distribution with increased percentage of the fast twitch, glycolytic, easily fatigable type IIb fibers (normal subjects, 22.7 +/- 10.1; heart failure, 33.1 +/- 11.1%; p less than 0.05), atrophy of type IIa (normal subjects, 5,477 +/- 1,109; heart failure, 4,239 +/- 1,247 microns 2; p less than 0.05) and type IIb fibers (normal subjects, 5,957 +/- 1,388; heart failure, 4,144 +/- 945 microns 2; p less than 0.01), and decreased activity of beta-hydroxyacyl CoA dehydrogenase (normal subjects, 5.17 +/- 1.44; heart failure, 3.67 +/- 1.68 mol/kg protein/hr; p less than 0.05). No significant linear correlation could be identified between the slope of the Pi/PCr to VO2 relation and muscle histochemistry or enzyme activities. Similarly, no linear relation was found between intracellular pH at peak exercise and any muscle variable.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contribution of intrinsic skeletal muscle changes to 31P NMR skeletal muscle metabolic abnormalities in patients with chronic heart failure. 280 70

Chronic stimulation of rat fast-twitch muscle increased the content of both fatty acid-binding protein (FABP) and myoglobin. The increases in FABP, which reached values close to that of cardiac muscle, exceeded those in myoglobin and those in citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities.
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PMID:Electrostimulation-induced increases in fatty acid-binding protein and myoglobin in rat fast-twitch muscle and comparison with tissue levels in heart. 292 22

Muscle homogenates representing slow-twitch oxidative, fast-twitch oxidative-glycolytic, fast-twitch glycolytic, and mixed fiber types were prepared from normal, diabetic, and insulin-treated diabetic rats. Diabetes was induced by injection of 80 mg . kg-1 of streptozotocin. The activities of citrate synthase, succinate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase were employed as markers of oxidative potential, whereas phosphorylase, hexokinase, and phosphofructokinase activities were used as an indication of glycolytic capacity. Diabetes was associated with a general decrement in the activity of oxidative marker enzymes for all fiber types except the fast-twitch glycolytic fiber. In contrast, the fast-twitch glycolytic fibers demonstrated the greatest decline in glycolytic enzymatic activity. Insulin-treated animals, either trained or untrained, exhibited enzyme activities similar to their normal counterparts. Exercise training of diabetic rats mimicked the effect of insulin treatment and caused a near normalization of the activity of the marker enzymes. These findings suggest that the enzymatic potential of all skeletal muscle fiber types of diabetic rats may be normalized by exercise training even in the absence of significant amounts of insulin.
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PMID:Influence of training on skeletal muscle enzymatic adaptations in normal and diabetic rats. 293 94


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