Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.1.1.27 (lactate dehydrogenase)
29,211 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the role of thyroid hormone in the postnatal development of Ca2+ transport activity of sarcoplasmic reticulum in skeletal muscle (m. gastrocnemius-plantaris). With a Ca2+-stat method using the fluorescent dye fura 2 as Ca2+ indicator, we determined the oxalate-supported maximal Ca2+ uptake activity of sarcoplasmic reticulum in whole muscle homogenates from neonatal rats. Expressed per g tissue wet wt, the activity increased nearly 10-fold during the first 8 weeks after birth, following which time a plateau was reached. This development was absent in hypothyroid pups, in which the level of Ca2+ uptake activity remained constant at 10% of the normal adult value for at least 8 weeks. When the mothers were given 0.05% propylthiouracil in the drinking water 1 week before parturition, these pups ceased to grow after 4 weeks, had a reduced muscle protein content and a characteristic cretinous appearance. The effects of hypothyroidism could be reversed by T3 treatment (0.5 micrograms/100 g BW, daily) starting 1 or 6 weeks after birth. Treatment with bovine GH (0.1 or 0.5 IU/100 g BW; daily) starting on day 5 stimulated body growth, particularly of muscle, but was without effect on the failing development of Ca2+ uptake activity. The postnatal rise in citrate synthase and succinate dehydrogenase activities was impaired in the hypothyroid group, but lactate dehydrogenase and creatine kinase activities rose continuously, although at a reduced rate. T3 treatment also reversed these effects of propylthiouracil. At the higher dosage used bovine GH appeared to stimulate the accumulation of creatine kinase. We conclude that the failing postnatal development of sarcoplasmic reticulum Ca2+ transport activity in hypothyroidism is not secondary to the absence of GH, nor is it part of a general, indiscriminate effect, but, rather, that it indicates an absolute requirement of thyroid hormone for this particular aspect of muscle differentiation.
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PMID:The postnatal development of sarcoplasmic reticulum Ca2+ transport activity in skeletal muscle of the rat is critically dependent on thyroid hormone. 291 9

This paper presents a study of the metabolic and contractile types of 34 samples from 30 muscles in five crossbred Pietrain-Large White pigs 6 to 7 months old. The activity of the following enzymes was measured: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase using high (LDH-h) or low (LDH-b) pyruvate concentrations in the reaction medium, citrate synthase (CS), and myofibrillar Ca-Mg activated ATPase. Haeminic iron and ultimate pH (pHu) were measured on the same samples. The results showed a negative, rather linear relationship between GAPDH, LDH and ATPase activities on the one hand and CS and haeminic iron on the other. Rather high correlations (r = 0.7 to 0.8) were observed between metabolic and contractile criteria and pHu; the red (slow) muscles had the highest pHu.
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PMID:[Enzyme metabolic and contractile activities of 30 pig muscles. Relation with the final ph attained after death]. 293 86

Activities of total creatine kinase (CK), its isoenzyme MB (CK-MB), total lactate dehydrogenase (LD) and its isoenzyme LD1, phosphofructokinase (PFK), aspartate aminotransferase (ASAT) and citrate synthase (CS) were determined in skeletal muscle biopsies obtained from physically trained and untrained men and in myocardial biopsies from patients subjected to open heart surgery because of valve disease. The LD1, ASAT and CS activities were higher in trained than in untrained skeletal muscle and still higher in heart muscle than in either trained or untrained skeletal muscle. The CK-MB activity was higher in trained than untrained skeletal muscle and the myocardial CK-MB activity was similar to that in trained skeletal muscle. Total CK activity was slightly lower in trained than in untrained skeletal muscle and the myocardial CK activity was approximately one third of the skeletal muscle CK. Both the PFK and the total LD activity was of similar magnitude in the different muscle types. In conclusion, as estimated by enzyme activities, the oxidative capacity is 2-3 times larger in myocardial than in skeletal muscle, while the glycolytic capacity as estimated by PFK appears to be the same.
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PMID:Activities of key enzymes in the energy metabolism of human myocardial and skeletal muscle. 294 12

The evaluation of the specific activity of some enzymes related to energy transduction was performed in 7 fresh samples of malignant gliomas and in 4 samples of normal brain tissue. Compared with normal brain tissue, the hexokinase, phosphofructokinase and citrate synthase activities are lower; the lactate dehydrogenase and succinate dehydrogenase are unchanged, while glucose-6-phosphate dehydrogenase and NADP+-isocitrate dehydrogenase activities are higher in gliomas.
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PMID:Enzymes related to energy metabolism in human gliomas. 294 16

Concentrations of high-energy phosphates and activities of key enzymes of energy metabolism were assessed in hearts from species with differing levels of cardiac power output. Positive correlations were found between resting power output and the total adenylate pool and between citrate synthase activity and the total adenylate pool. Maximum in vitro activity levels of enzymes from energy metabolism were compared with calculated resting cardiac power output and maximal cardiac power output (as reflected by total oligomycin-insensitive adenosine-triphosphatase activity). Three indexes of carbohydrate metabolism (hexokinase, pyruvate kinase, and L-lactate dehydrogenase) all plateau at relatively low levels of energy demand. In contrast, enzymes required for aerobic fatty acid metabolism, (carnitine palmitoyltransferase and 3-hydroxyacyl-CoA dehydrogenase) and for tricarboxylic acid and electron transport (citrate synthase and cytochrome-c oxidase) show consistent increases as ATP demand is elevated. It appears that as capacity for power development by vertebrate hearts, increases across taxa, the elevated demand for ATP is met by expansion of fatty acid based aerobic metabolism and not carbohydrate metabolism.
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PMID:Matching of vertebrate cardiac energy demand to energy metabolism. 295 61

The muscle enzymatic changes subsequent to 6 months of strength training followed by 3 months of detraining were examined in 21 physically active men. They were assigned either to a heavy-resistance (HR) or an explosive strength (EX) training program. Muscle biopsies were obtained from m. vastus lateralis for the assessment of activities of the enzymes hexokinase (HK), myofibrillar ATPase (ATPase), citrate synthase (CS), phosphofructokinase (PFK), lactate dehydrogenase (LDH), myokinase (MK) and creatine kinase (CK). The activities were measured on freeze-dried tissue samples using fluorometrical assays. Both groups displayed increased (P less than 0.01-0.001) fast-twitch (FT) fiber area consequent to training with no concomitant hypertrophy of slow-twitch (ST) fiber area. Mean fiber area increased by 16% (P less than 0.001) in HR and 9% (NS) in EX. Following detraining, mean fiber area returned to pretraining value only in EX. HK decreased in both groups (P less than 0.01-0.001) and CK decreased in HR (P less than 0.05). When the two groups were treated together, all enzymes, except for LDH, decreased their activity (P less than 0.05-0.001). It is concluded that 6 months of strength training performed either as heavy-resistance or explosive training is not associated with any increased activities of enzymes reflecting phosphagen, glycolytic, or oxidative metabolism. Instead, the present results suggest that exercise-induced hypertrophy is accompanied by attenuation of certain enzyme activities of importance for ATP regeneration.
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PMID:Enzymatic adaptations consequent to long-term strength training. 295 91

The adaptation of enzyme activities, notably in the oxidative metabolism, and of prerequisites for tissue transport of oxygen in the claudication leg was evaluated by comparing muscle biopsies from the gastrocnemius muscle of the claudication and the symptom-free leg of seven patients with unilateral claudication. The claudication leg had higher activities of a marker enzyme for mitochondrial oxidative capacity, citrate synthase (CS), as well as of the MB and the mitochondrial isoenzyme of creatine kinase (CK), which are considered to be involved in the transfer of high energy phosphate from the mitochondria to the resynthesis of ATP in the cytoplasm. The difference between claudication and healthy leg in activities of these CK isoenzymes were well correlated with the corresponding side difference in CS activity. No significant differences between claudication and healthy leg were found in distribution of muscle fibre types or fibre dimension, capillary density or myoglobin content, nor was there any side difference in phosphofructokinase or lactate dehydrogenase. Side differences tended to be greater in those patients with the most advanced obstructive arterial disease as estimated from non-invasive pressure measurements. It is concluded that in reasonably physically-active patients, the mode of ischaemia to which the claudication leg is subjected leads to a metabolic adaptation characterized by increased activities of enzymes involved in the oxidative metabolism, but no significant adaptation of either the conditions for local oxygen transport, as estimated by myoglobin content, and capillary density, or capacity for anaerobic metabolism.
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PMID:Calf muscle adaptation in intermittent claudication. Side-differences in muscle metabolic characteristics in patients with unilateral arterial disease. 296 71

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


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