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 activities of enzymes related to energy metabolism in the gastrocnemius and soleus muscles in young-adult (4 months), mature (12 months), and senescent (24 months) rats were compared after continuous (72 consecutive h) exposure to normobaric hypoxia or normoxia after the vasodilator naftidrofuryl or saline solution had been given intraperitoneally for 30 consecutive days. The maximum rats (Vmax) of the following enzyme activities in the crude extract and/or the crude mitochondrial fraction of each muscle specimen were evaluated for: the anaerobic glycolytic pathway (hexokinase, phosphofructokinase, pyruvate kinase, and lactate dehydrogenase), the tricarboxylic acid cycle (citrate synthase, and malate dehydrogenase), the electron transfer chain (cytochrome oxidase), and the NAD+/NADH redox state (total NADH cytochrome c reductase). The significance of differences between the enzyme activities at different ages or under different experimental conditions in the two tissue preparations of the two muscles were determined by ANOVA. MCA and ETA2 were used to evaluate the net effects of the experimental conditions. First, aging did not seem to affect the soleus and gastrocnemius muscles in the same way. In the gastrocnemius muscle, the major changes were seen in enzymes of the glycolytic pathway, in the crude extracts. In the soleus muscle, the more striking changes in enzyme activities as a function of aging were found in the crude mitochondrial fraction. We also found that hypoxia caused more important changes in 12-month-old rats than in those of other ages (especially the enzyme activities of the gastrocnemius muscle). Naftidrofuryl modified the effects of hypoxia only sometimes and further investigations are necessary before we can draw any conclusions about the pharmacological activity of naftidrofuryl in hypoxia.
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PMID:Effects of hypoxia and pharmacological treatment on enzyme activities in skeletal muscle of rats of different ages. 164 27

Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose-6-phosphate, pyruvate, lactate), Krebs cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate), related free amino acids (glutamate, alanine), ammonia, energy store (creatine phosphate), energy mediators (ATP, ADP, AMP) and energy charge potential were evaluated. Furthermore the maximum rate (Vmax) of the following muscular enzyme activities was evaluated in the crude extract and/or mitochondrial fraction: for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase; for the tricarboxylic acid cycle: citrate synthase, malate dehydrogenase; for the electron transfer chain: total NADH cytochrome c reductase, cytochrome oxidase. The rat gastrocnemius muscles were analyzed in normoxia and after repeated, alternate hypoxic and normoxic exposures (12 hours of hypoxia daily; for 5 days). Naftidrofuryl was administered daily at three different doses: 10, 15 and 22.5 mg/kg i.m., 30 min before the beginning of the experimental hypoxia. The biochemical adaptation to intermittent normobaric hypoxic-normoxic exposures was characterized by the decrease of the muscular contents of creatine phosphate, citrate, alpha-ketoglutarate and glutamate. This adaptation occurred in absence of significant changes in the Vmax of the muscle enzymes tested. By naftidrofuryl treatment, in gastrocnemius muscle from hypoxic rats both alpha-ketoglutarate and creatine phosphate contents maintained normal values, while glutamate concentration remained reduced to subnormal values. With the exception of hexokinase, naftidrofuryl treatment did not modify the Vmax of marker enzymes related to energy transduction.
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PMID:Adaptation of skeletal muscle energy metabolism to repeated hypoxic-normoxic exposures and drug treatment. 401 59