Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eighteen patients with severe COPD and seven healthy control subjects 64.0 +/- 2.2 and 66.8 +/- 1.4 yr of age, respectively (mean +/- SEM), were investigated. Arterial blood gas analysis, dynamic lung volumes, and muscle biopsy specimens from the quadriceps femoris muscle were performed. The muscle biopsies were analyzed for citrate synthase (CS), succinic acid dehydrogenase (SDH), 3-hydroxyacyl-CoA dehydrogenase (HAD), phosphofructokinase (PFK), and lactate dehydrogenase (LDH) activities and related to protein content. The PFK activity was higher in the COPD group than in the control group (+34%, p < 0.05). CS showed a group difference in the opposite direction (-29%, p < 0.05). LDH activity followed PFK and tended to be higher in the patient group (+27%, NS), whereas SDH (-31%, NS) and HAD (-28%, NS) mirrored the CS results. Muscle protein concentration tended to be lower in the COPD group (-14%, NS). There were no significant changes in enzyme activity after 7 mo of long-term oxygen therapy (n = 6). These results indicate adaptation in the form of augmented glycolysis (PFK), and decreased aerobic metabolism (CS) in the quadriceps femoris muscle in patients with advanced COPD.
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PMID:Metabolic enzyme activity in the quadriceps femoris muscle in patients with severe chronic obstructive pulmonary disease. 766 93

These experiments examined the metabolic properties of the canine respiratory muscles. Because the costal diaphragm (COD), crural diaphragm (CRD), parasternal intercostals (PI), triangularis sterni (TS), and transversus abdominis (TA) are active during quite breathing in the dog, we hypothesized that these muscles would have different metabolic profiles (i.e., higher oxidative and antioxidant enzyme activities) compared with ventilatory muscles recruited only at increased ventilatory requirements [e.g., scalene (SC) and external oblique (EO)] and locomotor muscles [e.g., deltoid (DEL)]. To test this hypothesis, muscle samples were removed from six healthy adult dogs and analyzed to determine the activities of citrate synthase (CS), phosphofructokinase (PFK), 3-hydroxyacyl-CoA dehydrogenase (HADH), and superoxide dismutase (SOD). The activities of these enzymes were interpreted as relative measures of metabolic capacities, and enzyme activity ratios were considered as representing relationships between different metabolic pathways. Analysis revealed that CS and HADH activities were significantly higher (P < 0.05) in the PI, COD, CRD, and TS compared with those in all other muscles. Muscles with the lowest CS, HADH, and SOD activities (i.e., SC, TA, EO, DEL) generally had the highest PFK activities, Furthermore, the PFK/CS ratio was significantly lower in the PI, COD, CRD, and TS compared with that in all other muscles studied. These data support the notion that the canine PI, COD, CRD, and TS are metabolically different from other key ventilatory muscles.
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PMID:Metabolic characteristics of primary inspiratory and expiratory muscles in the dog. 786 32

Although chronic cocaine use is cardiotoxic, its use remains problematic in athletics. Hence adaptive changes induced in the heart by superimposing chronic cocaine use on an exercise training are of interest but remain poorly understood. Therefore this study investigated the effects of cocaine treatment combined with exercise training on the metabolic and contractile properties of the heart. Male Sprague-Dawley rats were assigned to one of four groups: normal sedentary (NS, n = 6), cocaine sedentary (CS, n = 6), normal trained (NT, n = 6), and cocaine trained (CT, n = 6). Trained animals were sprint trained 4 times/week. CS and CT animals received cocaine (25 mg/kg, ip) 6 times/week, 15 min before each exercise bout and 2 additional times per week. After 12 weeks, all animals were sacrificed, and the hearts were removed and analyzed for citrate synthase activity, 3-hydroxyacyl-CoA dehydrogenase activity, Ca(2+)-activated myofibrillar ATPase activity, and myosin isoform distribution. None of the groups demonstrated altered cardiac metabolic properties, but cocaine alone and in conjunction with exercise reduced myofibrillar ATPase activity (p < 0.05) and increased expression of the low ATPase myosin isoform, V3. These data suggest that the potential of the citric acid cycle and beta-oxidation is not sensitive to chronic cocaine treatment, but the distribution of cardiac myosin among its three isoforms is affected. Furthermore, high-intensity treadmill training does not interact with cocaine to further alter these properties.
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PMID:Effects of long-term cocaine administration and exercise on cardiac metabolism and isomyosin expression. 801 90

A new, sensitive assay for the quantitative determination of AMP deaminase activity in human skeletal muscle is presented. The method is based on the determination of the direct product of the AMP deaminase reaction, the formed IMP, by high performance liquid chromatography (HPLC). In order to evaluate the relationship between AMP deaminase activity on the one hand and the contractile and metabolic characteristics of the muscle and the physical performance on the other, muscle biopsies were taken from 20 male subjects. The subjects also performed a 30 s sprint test on a cycle ergometer. The inter-individual variation in AMP deaminase activity was large, ranging from 5.4 to 27.4 microkat g-1 dry muscle. AMP deaminase was positively correlated with phosphofructokinase (PFK), the marker of the glycolytic capacity of the muscle, but there was no correlation with enzymes of oxidative metabolism, such as 3-hydroxyacyl-CoA dehydrogenase and citrate synthase, or with the activity of myokinase and lactate dehydrogenase. There was no significant correlation between AMP deaminase activity and the proportion of the different muscle fibre types. A weak positive correlation was found between the sprint performance and the AMP deaminase activity. In conclusion, the HPLC assay was found to be a fast, sensitive and reliable method for the quantitative determination of AMP deaminase activity in muscle. A direct relationship between AMP deaminase activity on the one hand and glycolytic capacity and sprint performance on the other was found. However, no relationship to oxidative capacity or contractile properties was found.
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PMID:AMP deaminase in skeletal muscle of healthy males quantitatively determined by new assay. 803 9

Selected enzymes were measured in mixed-fiber bundles and individual fibers from rat plantaris (PL) and soleus (Sol) muscles that had undergone either 2 wk of tetrodotoxin (TTX) inactivation of the sciatic nerve, a sham operation, or were contralateral to the TTX limb. TTX disuse caused severe wasting of PL (46%) and Sol (26%) muscles and of single fibers (50% and 40%, respectively). TTX PL and Sol also had reduced (50%) glycogen content. In TTX, PL, and Sol macro samples and single fibers, the activities (mol.h-1.kg dry wt-1) of hexokinase, glycogen phosphorylase, and lactate dehydrogenase were higher, lower, and unchanged, respectively, compared with controls. Single-fiber data showed that these changes occurred in all fibers. In TTX PL macro samples, activities of glycerol-3-phosphate dehydrogenase (GPDH), pyruvate kinase (PK), malate dehydrogenase (MDH), citrate synthase (CS), beta-hydroxyacyl-CoA dehydrogenase (BOAC), and thiolase were, or tended to be, lower. Single-fiber data showed a disappearance of high-oxidative moderate glycolytic fibers (i.e., usually fast-twitch oxidative in control) and the appearance of more fibers with a metabolic enzyme profile approaching that of control slow-oxidative fibers. In TTX Sol macro samples, GPDH and PK tended to be higher, and thiolase, BOAC, CS, and MDH lower. Single-fiber data corroborated these findings and suggested the appearance of fast fibers with downregulated oxidative enzyme profiles. Our results suggest that neuromuscular activity is a major, but not the sole, determinant of the size and metabolic heterogeneity that exists in muscle cells.
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PMID:Effects of tetrodotoxin-induced neural inactivation on single muscle fiber metabolic enzymes. 804 92

Disruption of cellular constituents including inhibition or "downregulation" of metabolic enzyme activity has been associated with free radical stress in locomotor muscle with acute, strenuous exercise. However, the effects of acute, strenuous exercise on important metabolic and antioxidant enzyme activity levels in the diaphragm are unknown. Twenty 4-month-old and twenty 24-month-old female Fischer-344 rats were divided at random into young exercised (YE; n = 10)/old exercised (OE; n = 10); young control (YC; n = 10)/old control (OC; n = 10) groups. Animals in both young and old exercise groups ran on a treadmill (10% uphill grade) for 40 min at approximately 75% of age group VO2 max. Immediately following the treadmill run, both exercise and control groups were euthanized with sodium pentobarbital. Costal (COD) and crural diaphragm (CRD) were quickly removed and frozen in liquid nitrogen. Lipid peroxidation was significantly increased (P < 0.05) in COD of YE vs. YC rats. Activity of the antioxidant enzyme glutathione peroxidase (GPX) was unaltered in the diaphragm by acute exercise (P > 0.05) in both age groups. There was a significant increase in superoxide dismutase (SOD) activity with exercise (P < 0.05). Post-hocs revealed SOD activity was approximately 20% greater (P = 0.066) in YE CRD only. Activities of the metabolic enzymes phosphofructokinase (PFK), succinate dehydrogenase (SDH), and citrate synthase (CS) were not affected by acute exercise in YE or OE. Strenuous exercise resulted in a small trend towards a decrease in 3-hydroxyacyl-CoA dehydrogenase (HADH) activity in YE COD (P = 0.115) and YE CRD (P = 0.082). We conclude that the employed bout of exercise induces some free radical stress, while metabolic enzymes are protected, in the diaphragm.
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PMID:Metabolic and antioxidant enzyme activities in the diaphragm: effects of acute exercise. 805 80

We tested the hypothesis that a chronically active muscle, such as the rat diaphragm, would be more resistant to glucocorticoid-induced myopathy than a less active locomotor skeletal muscle (plantaris). Furthermore, we sought to determine whether endurance exercise could antagonize the glucocorticoid-induced atrophy in the diaphragm. Rats were assigned to one of seven experimental groups (n = 10 per group) and injected daily over a 10-day period with either a sham solution or prednisolone acetate: group 1: control; sedentary and sham injected; group 2: control; exercise trained and sham injected; group 3; sedentary; prednisolone (0.5 mg.kg-1 x day-1); group 4: sedentary; prednisolone (1.0 mg.kg-1 x day-1); group 5: sedentary; prednisolone (2.0 mg.kg-1 x day-1); group 6: sedentary; prednisolone (5.0 mg.kg-1 x day-1); group 7: exercise trained; prednisolone (5.0 mg.kg-1 x day-1). Slope differences in the dose-response curves suggest that prednisolone-induced muscle atrophy in the plantaris was more severe than that in the diaphragm. Furthermore, high doses of prednisolone resulted in a differential effect on muscle bioenergetic enzyme activities in the plantaris and diaphragm. Prednisolone treatment (> or = 2 mg.kg-1 x day-1) resulted in a significant reduction in phosphofructokinase activity (expressed as microM substrate.min-1 x mg protein-1) and an increase in 3-hydroxyacyl-CoA dehydrogenase activity in the plantaris muscle. In contrast, prednisolone treatment did not influence phosphofructokinase activity (P > 0.05) in the diaphragm but decreased (P < 0.05) relative citrate synthase activity. Finally, 90 min daily of endurance exercise did not antagonize prednisolone-induced myopathy in either the diaphragm or the plantaris.
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PMID:Exercise and glucocorticoid-induced diaphragmatic myopathy. 822 80

Inhibition of metabolic enzyme activity has been associated with free radical stress in locomotor muscle with prolonged or intense exercise. However, it is not known whether such alterations with acute exercise in skeletal muscle are influenced by muscle fiber type or age. Twenty 4-mo-old and twenty 24-mo-old female Fischer-344 rats were divided at random into young exercised (YE; n = 10), old exercised (OE; n = 10), young control (YC; n = 10), and old control (OC; n = 10) groups. Animals in both YE and OE groups ran on a treadmill (10% uphill grade) for 40 min at approximately 75% of each age-group's maximal O2 consumption. Immediately after the treadmill run, white gastrocnemius (WG), red gastrocnemius (RG), and soleus (SOL) muscles were removed and quick-frozen in liquid nitrogen. Malondialdehyde was significantly increased (P < 0.05) in RG of YE vs. YC rats. Glutathione peroxidase activity was significantly elevated (P < 0.05) in the WG of YE rats. Analysis of variance revealed a significant over-all increase in superoxide dismutase activity with exercise. Activities of phosphofructokinase (PFK), citrate synthase, succinate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase were unchanged (P > 0.05) with acute exercise in the SOL. However, PFK activity was decreased in the WG by 60% in OE but only 33% in YE, and in the RG by 41% in OE but only 21% in YE. We conclude that maximal glycolytic flux in the gastrocnemius may be adversely affected by acute exercise, and this effect was more pronounced in the 24-mo-old group.
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PMID:Acute exercise and skeletal muscle antioxidant and metabolic enzymes: effects of fiber type and age. 828 76

The purpose of this study was to evaluate the physiologic responses to endurance training in patients with moderate to severe airflow obstruction by specifically looking at changes in skeletal muscle enzymatic activities. Eleven patients (age = 65 +/- 7 yr, mean +/- SD, FEV1 = 36 +/- 11% of predicted value, range = 24 to 54%) were evaluated before and after an endurance training program. Each evaluation included a percutaneous biopsy of the vastus lateralis and a stepwise exercise test on an ergocycle up to his/her maximal capacity. VE, VO2, VcO2, and serial arterial lactic acid concentration were measured during the exercise test. The activity of two oxidative enzymes, citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HADH), and of three glycolytic enzymes, lactate dehydrogenase, hexokinase, and phosphofructokinase was determined. The training consisted of 30-min exercise sessions on a calibrated ergocycle, 3 times a week for 12 wk. The aerobic capacity was severely reduced at baseline (VO2max = 54 +/- 12% of predicted) and increased by 14% after training (p < 0.05). For an identical exercise workload, there was a significant reduction in VE (34.5 +/- 10.0 versus 31.9 +/- 9.0 L/min, p < 0.05) and in arterial lactic acid concentration (3.4 +/- 1.3 versus 2.8 +/- 0.9 mmol/L, p < 0.01) after training. The lactate threshold also increased after training (p < 0.01) while the activity of the three glycolytic enzymes was similar at the two evaluations. In contrast, the activity of CS and HADH increased significantly after training (22.3 +/- 3.5 versus 25.8 +/- 3.8 mumol/min/g muscle for CS, p < 0.05, and 5.5 +/- 2.9 versus 7.7 +/- 2.5 mumol/min/g for HADH, p < 0.01). A significant inverse relationship was found between the percent changes in the activity of CS and HADH, and the percent changes in arterial lactic acid during exercise (p = 0.01). We conclude that endurance training can reduce exercise-induced lactic acidosis and improve skeletal muscle oxidative capacity in patients with moderate to severe chronic obstructive pulmonary disease (COPD).
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PMID:Skeletal muscle adaptation to endurance training in patients with chronic obstructive pulmonary disease. 875 20

Chronic electrical stimulation of skeletal muscle at 10 Hz induces fast-to-slow fiber type transformation. Does a lower aggregate amount of activity lead to a less complete transformation, or does it produce the same transformation over a longer time course? We examined this question by subjecting adult rabbit tibialis anterior and extensor digitorum longus muscles to continuous stimulation at 2.5 Hz for 2-12 wk. Most of the fibers acquired the histochemical and immunocytochemical characteristics of type 2A, not type 1, fibers. There was a corresponding rise in oxidative activity, but this was accompanied by a marked decline in anaerobic glycolysis. The activities of hexokinase and 3-oxoacid CoA-transferase stopped increasing after 2 wk, glutamate oxaloacetate transaminase after 4 wk, and beta-hydroxyacyl-CoA dehydrogenase after 6 wk of stimulation. Succinate dehydrogenase, citrate synthase, lactate dehydrogenase, and creatine phosphokinase continued to change up to 12 wk of stimulation. Changes in enzyme activity were not as rapid or as marked as those observed for stimulation at 10 Hz, and none showed the typical two-phase response of oxidative enzyme activities to stimulation at 10 Hz. The latter may therefore be dependent on induction of type 1 myosin isoforms.
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PMID:Induction of a fast-oxidative phenotype by chronic muscle stimulation: histochemical and metabolic studies. 877 59


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