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)

Myoglobin (Mb) content and citrate synthase (CS) activity were determined in myocardial samples from nine human brain-dead organ donors with normal hearts. Six regions of each heart were analyzed: right and left atria, right ventricle, left ventricular subepicardium, subendocardium, and anterior papillary muscle. The Mb content was similar, whereas the CS activity was higher in the left than in the right heart at both atrial and ventricular levels. Mb content and CS activity were higher in ventricles than in atria. The subendocardial layer and papillary muscle of the left ventricle had a higher Mb content than the subepicardial layer, whereas CS activity was similar in these three locations. The results suggested a closer relationship between CS activity (oxidative potential) and work load than between Mb content and work load. Mb content may, instead, be related to intramuscular oxygen tension (PO2) on the basis of a comparison between our Mb data and those of others on regional variations in myocardial PO2.
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PMID:Myoglobin content and citrate synthase activity in different parts of the normal human heart. 224 77

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

Myoglobin, muscle fibre diameter, and citrate synthase activity were measured in leg muscle of untrained and trained men and in the myocardium from the apex of the left ventricle and from papillary muscle in patients subjected to open heart surgery. The citrate synthase (CS) activity was 60% higher in trained than in untrained skeletal muscle. In the myocardium it was around four times greater than in untrained skeletal muscle but there was no difference between the apex of the left ventricle and papillary muscle. The fibre diameter varied almost threefold between the different groups of muscles with the largest diameter in untrained skeletal muscle and the with the largest diameter in untrained skeletal muscle and the smallest in papillary muscle. The myoglobin content in trained skeletal muscle did not differ from that of untrained muscle. In the left ventricle it was only 40% of that found in untrained muscle while papillary muscle had almost twice as high a myoglobin content as did the left ventricle. The ratio between myoglobin and fibre diameter, however, was of similar magnitude in skeletal muscle and the left ventricle while it was twice as high in papillary muscle as in the other muscles. In conclusion, the diffusion distance in terms of fibre diameter decreased with increased oxidative capacity (CS activity), when comparing the statistical means of the four different groups. The capacity for oxygen diffusion in relation to oxygen demand measured as the ratio of myoglobin to fibre diameter appeared to be of similar magnitude in skeletal muscle and left ventricle but was higher in papillary muscle.
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PMID:Myoglobin content in human skeletal muscle and myocardium: relation to fibre size and oxidative capacity. 674 65

Male rats were either sham-operated (N) or castrated (C) at 65 days of age. They were further subdivided into sedentary or exercise groups that were trained by treadmill running 5 days/wk for 12 wk. During the last 10 days of training, the animals received daily subcutaneous injections of cortisone acetate (CA) (100 mg/kg) or 1% carboxymethylcellulose. Body weight decreased approximately 25% in all groups that received CA. The fast-twitch plantaris and gastrocnemius muscle weights were approximately 35% lower in CA-treated versus cortisone-free N and C sedentary animals. Exercise prevented from one-fourth to one-half of the muscle weight loss in N and C runners when compared to their respective pair weight controls. Muscle weights of the CA-treated freely eating N controls were significantly less than that of N runners that received CA. In plantaris muscles of both N and C animals that received CA, total protein concentration and citrate synthase activity, a mitochondrial marker, remained constant, but their amounts per muscle decreased in proportion to the atrophy. However, myoglobin concentration increased in plantaris muscles of CA-treated animals, although total myoglobin per muscle was reduced slightly. Myoglobin levels were increased in plantaris muscles both as a result of training and CA, but citrate synthase activity was increased only as a result of the exercise. These results show that exercise can retard the glucocorticoid-induced muscle atrophy.
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PMID:Partial prevention of glucocorticoid-induced muscle atrophy by endurance training. 728 23

It is not known precisely how marine mammals are able to maintain muscle function during active swimming in breath-hold dives, when ventilation stops and heart rate falls. Examination of muscle biochemistry and histochemistry can provide information on the relative importance of different metabolic pathways, the contractile potential of the muscle fibres, the oxygen storage capacity of the muscle and the capillary distribution in these animals. In this study, samples of locomotory muscle were taken from wild grey seals (Halichoerus grypus), harbour seals (Phoca vitulina) and Antarctic fur seals (Arctocephalus gazella); Wistar rat muscle was analysed for comparative purposes. Activities of citrate synthase and beta-hydroxyacyl CoA dehydrogenase were higher in the harbour seal muscle than in the grey seal muscle, suggesting that harbour seals have a greater aerobic capacity. Both phocid muscles had a greater reliance on fatty acid oxidation than the fur seal or rat muscles. The myoglobin data demonstrate that the grey seals have the highest oxygen storage capacity of the three pinniped species, which correlates with their greater diving ability. Myoglobin levels were higher in all three pinniped species than in the Wistar rat. The fibre type compositions suggest that the muscles from the fur seals have higher glycolytic capacities than those of the phocid seals [fur seal pectoralis, 7% slow-twitch oxidative fibres (SO), 25% fast-twitch oxidative glycolytic fibres (FOG), 68% fast-twitch glycolytic fibres (FG); grey seal 57% SO, 5% FOG, 38% FG; area per cents]. However, the pectoralis muscle of the fur seal, although the most glycolytic of the pinniped muscles studied, has the highest capillary density, which indicates a high capacity for fuel distribution. These results show that, while pinniped muscle has an increased oxygen storage potential compared with the muscle of a typical terrestrial mammal, there are no distinct adaptations for diving in the enzyme pathways or fibre type distributions of the pinniped muscle. However, the muscle characteristics of each species can be related to its diving behaviour and foraging strategy.
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PMID:The metabolic characteristics of the locomotory muscles of grey seals (Halichoerus grypus), harbour seals (Phoca vitulina) and Antarctic fur seals (Arctocephalus gazella). 796 4

Endurance exercise training increases the oxidative capacity of skeletal muscles, reflecting the induction of genes encoding enzymes of intermediary metabolism. To test the hypothesis that changes in gene expression may be triggered specifically during recovery from contractile activity, we quantified c-fos, alpha B-crystallin, 70-kDa heat shock protein (hsp70), myoglobin, and citrate synthase RNA in rabbit tibialis anterior muscle during recovery from intermittent (8 h/day), low-frequency (10 Hz) motor nerve stimulation. Recovery from a single 8-h bout of stimulation was characterized by large (> 10-fold) transient increases in c-fos, alpha B-crystallin, and hsp70 mRNA. Similar changes were noted during recovery after 7 or 14 days of stimulation (8 h/day). Myoglobin and citrate synthase mRNA were also induced during recovery, but the changes were of lesser magnitude (2- to 2.5-fold) and were observed only following repeated bouts of muscle activity (7th or 14th day) that promoted sustained (> 24 h) increases in these transcripts. These findings indicate that recovery from exercise is associated with specific transient changes in the expression of immediate early and stress protein genes, suggesting that the products of these genes may have specific roles in the remodeling process evoked by repeated bouts of contractile activity.
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PMID:Transient regulation of c-fos, alpha B-crystallin, and hsp70 in muscle during recovery from contractile activity. 948 22

The objective was to assess the aerobic capacity of skeletal muscles in pinnipeds. Samples of swimming and nonswimming muscles were collected from Steller sea lions (Eumetopias jubatus, n = 27), Northern fur seals (Callorhinus ursinus, n = 5), and harbor seals (Phoca vitulina, n = 37) by using a needle biopsy technique. Samples were either immediately fixed in 2% glutaraldehyde or frozen in liquid nitrogen. The volume density of mitochondria, myoglobin concentration, citrate synthase activity, and beta-hydroxyacyl-CoA dehydrogenase was determined for all samples. The swimming muscles of seals had an average total mitochondrial volume density per volume of fiber of 9.7%. The swimming muscles of sea lions and fur seals had average mitochondrial volume densities of 6.2 and 8.8%, respectively. These values were 1.7- to 2.0-fold greater than in the nonswimming muscles. Myoglobin concentration, citrate synthase activity, and beta-hydroxyacyl-CoA dehydrogenase were 1.1- to 2. 3-fold greater in the swimming vs. nonswimming muscles. The swimming muscles of pinnipeds appear to be adapted for aerobic lipid metabolism under the hypoxic conditions that occur during diving.
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PMID:High aerobic capacities in the skeletal muscles of pinnipeds: adaptations to diving hypoxia. 1019 10