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 purpose of this study was to determine whether thyroid hormone could directly affect the phenotypic expression of two isozymic systems [lactate dehydrogenase (LDH) and myosin] and the energy transducing potential of cultured neonatal heart cells. In addition we determined if these biochemical systems developed in culture as they normally do during in vivo post-natal development. Cells were maintained for 14 days in culture medium containing 10% horse serum and Earle's salts. Experimental cultures were supplemented with 10 nmol/l 3,3',5-triiodo-L-thyronine (T3). Hearts used to study in vivo development were excised from rats at the ages of 2 and 14 days post-natal to correspond with the time of isolating and harvesting the cultured heart cells, respectively. Adult hearts were used to represent the final developmental stage. Cultured cardiomyocytes without T3 administered to the culture medium showed no change in the isozymic profiles (myosin and LDH) or in metabolic potential during the 2 week culture period. The T3 treated cultures showed a complete shift to the V1 myosin isozyme. The glycolytic and aerobic metabolic potential [i.e., phosphofructokinase (PFK) and citrate synthase (CS) activities] and the LDH isozyme distribution were unaltered by T3 treatment. During in vivo development a shift toward the V1 myosin and H-LDH isozymes along with an increase in aerobic metabolism occurred in the rat heart. These findings indicate that the development of these selected biochemical systems in cultured cardiac myocytes does not result from an intrinsic myogenetic program and thus must be regulated in vivo by epigenetic factor(s). These results show that T3 has the potential to be the prime determinant of the phenotypic expression of the myosin isoforms, but does not have the potential to be the sole determinant for the expression of the LDH isozymes or the glycolytic (PFK) and aerobic (CS) capacities of cardiac muscle cells.
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PMID:The effects of triiodothyronine on cultured neonatal rat cardiac myocytes. 297 10

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

Biopsies from m. quadriceps femoris from the operated leg of nine patients were taken before, and 6 weeks after, knee surgery. During the whole postoperative period the operated leg was immobilized with the knee in 40-50 degrees of flexion. Myoglobin (MYO) and the enzymes citrate synthase (CS), creatine kinase (CK) and its isozymes MB (CK-MB) and mitochondrial CK (CK-MIT), aspartate aminotransferase (ASAT), phosphofructokinase (PFK) and lactate dehydrogenase (LD) were determined on the biopsies. Citrate synthase, ASAT, CK, CK-MB, CK-MIT and LD activities were decreased (12-30%) after the postoperative leg immobilization period. Phosphofructokinase did not change, while MYO content was increased (16%). In conclusion, a different control of the synthesis of oxidative enzymes and MYO is suggested, as the induced changes following immobilization were in opposite directions. The function of the increased MYO content may be to facilitate the oxygen extraction.
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PMID:Increase in myoglobin content and decrease in oxidative enzyme activities by leg muscle immobilization in man. 297 30

The effect of physical training on the in vitro activities of key enzymes that provide quantitative information on the maximum capacities of anaerobic and aerobic metabolism has been investigated in the gluteal muscle of the horse. Training had no effect on the activities of 6-phosphofructokinase or creatine kinase, suggesting that there was no effect on the capacity of anaerobic metabolism in this muscle. However, the activities of hexokinase and citrate synthase were increased, indicating that training increased the capacity of aerobic metabolism. For comparative purposes, muscle fibre composition and enzyme activities were also determined in a group of foals and a group of broodmares.
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PMID:Activities of key enzymes of aerobic and anaerobic metabolism in middle gluteal muscle from trained and untrained horses. 299 78

In the present study the effects of chronic administration of dextroamphetamine on energy metabolism in the brain of the rat were examined. The enzymes studied were: hexokinase (soluble and particulate forms), phosphofructokinase, pyruvate kinase, lactate dehydrogenase, citrate synthase, NAD+ and NADP+-dependent isocitrate dehydrogenases, succinate dehydrogenase and malate dehydrogenase. All the activities of the enzymes were assayed in four regions of the brain of the rat (cerebellum, medulla oblongata and pons, cererbral cortex and diencephalon). Rats were injected intaperitoneally once daily with dextroamphetamine for 20 consecutive days. The initial dose was 5 mg/kg/day and the dose was then increased by 1 mg/kg/every 5 days up to a total of 8 mg/kg/day on days 16-20. In the glycolytic enzymes a reduction of the activity of phosphofructokinase was found in the diencephalon and an increase of the activity of pyruvate kinase and lactate dehydrogenase in the diencephalon and medulla oblongata and pons, respectively. Citrate synthase was the only enzyme in the Krebs' cycle affected by chronic administration of dextroamphetamine. The results presented here show that chronic administration of dextroamphetamine produced important changes in some enzymes of glycolysis and the Krebs' cycle in the brain of the rat.
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PMID:Effects of chronic administration of dextroamphetamine on enzymes of energy metabolism in regions of the rat brain. 303 25

The ultrastructure of skeletal muscle and activity of some enzymes of energy metabolism were studied to assess the effect of a deficiency of dietary energy and subsequent nutritional rehabilitation in 24 young, growing, healthy rhesus monkeys. Electron microscopy of muscles on energy-deficient animals showed thinning of myofibrils with widening of interfibrillar space and enlargement and accumulation of mitochondria at subsarcolemmal level. There was an apparent significant reduction in the fiber size. Muscle samples from each animal were analyzed for enzymes representative of glycolysis (phosphofructokinase [PFK] and lactate dehydrogenase [LDH], citric-acid cycle (isocitric dehydrogenase [ICDH] and citrate synthase [CS] and regeneration of ATP (creatine kinase [CK]. PFK and LDH activities were significantly augmented in energy-deficient animals. The increase in LDH activity resulted from a large increase in MU (skeletal muscle) LDH subunit. The activities of CS and ICDH were reduced. No alteration of CK in muscle and serum was observed. The morphological structure and enzyme activities returned to normal after nutritional rehabilitation.
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PMID:Ultrastructure and activity of some enzymes of energy metabolism of skeletal muscle in experimental energy deficiency. 310 25

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

Tibialis anterior (TA) muscle of mouse, rat, guinea pig, and rabbit was indirectly stimulated for 10 h/day at 10 Hz up to 28 days. Changes in the activity levels of hexokinase (HK), phosphofructokinase (PFK), glyceraldehydephosphate dehydrogenase (GAPDH), lactate dehydrogenase (LDH), creatine kinase (CK), citrate synthase (CS), malate dehydrogenase (MDH), 3-hydroxyacyl-CoA dehydrogenase (HADH), and beta-hydroxybutyrate dehydrogenase (HBDH) were compared. Although the direction of changes in the enzyme activity pattern was in accordance with previous findings on rabbit TA, the magnitude of the responses varied markedly between the mammals under study. Mouse TA was almost unaffected. A major effect of chronic stimulation in rat, guinea pig and rabbit was an increase in enzyme activities of aerobic-oxidative metabolism. According to intrinsic differences of the muscles under study, the increases varied among the species and appeared to be inversely related to the basal levels of these enzymes in the unstimulated muscles. Conversely, glycolytic enzyme activities (PFK, GAPDH, LDH) markedly decreased in rat, guinea pig, and rabbit, and were only slightly reduced in mouse. Changes in HK and HBDH activities displayed the largest variations in the induced change between species. These results indicate species-specific patterns of metabolic adaptation to increased contractile activity.
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PMID:Species-specific effects of chronic nerve stimulation upon tibialis anterior muscle in mouse, rat, guinea pig, and rabbit. 317 88

Some key enzyme activities from the energy metabolism of A. pullulans have been studied during the ethanol-induced yeast-to-mycelium transition. Both the mycelial and yeast-like forms showed greater glucose-6-phosphate dehydrogenase activity than phosphofructokinase. During the morphological transition, the most outstanding variations occurred in large cells (3 days), especially for citrate synthase, malate dehydrogenase and isocitrate lyase activities. However, similar variations were detected in cultures without glucose or ethanol, which showed no morphological transition. Therefore, the observed changes in the enzymatic activities may be attributed to the absence of glucose. As this is not sufficient to induce the morphological transition, we conclude that there is no evidence of a clear-cut relationship between morphology and the activity of the enzymes studied.
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PMID:[Evolution of several enzyme activities of Aureobasidium pullulans during the transition from yeast to mycelium induced by ethanol]. 326 91

We studied energy metabolism after experimental subarachnoid hemorrhage in rats. Four different cerebral areas were tested: frontal cortex, occipital cortex, hippocampus, and brainstem. Vmax of the following enzymatic activities was evaluated: in the homogenate: hexokinase, phosphofructokinase, and lactate dehydrogenase for the glycolytic pathway, and glucose-6-phosphate dehydrogenase for the hexose monophosphate shunt; in the purified nonsynaptic mitochondria: NAD+-isocitrate dehydrogenase, citrate synthase, and succinate dehydrogenase for the Krebs cycle, and cytochrome oxidase for the electron transfer chain. We also evaluated some parameters related to the respiration of nonsynaptic mitochondria (State 3, State 4, uncoupled state, respiratory control ratio, and ADP:O ratio). Subarachnoid hemorrhage did not significantly affect Vmax of the enzymatic activities related to anaerobic and aerobic metabolism; however, mitochondrial respiration was affected, particularly in the presence of NADH-producing substrates (glutamate + malate).
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PMID:Bioenergetics of different brain areas after experimental subarachnoid hemorrhage in rats. 335 25


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