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 fatigue characteristics and the activities of oxidative and glycolytic enzymes were determined in tetrodotoxin (TTX)-induced disuse muscles and in muscles of animals recovering from TTX-induced disuse (TTX-rec). In addition, the effects of additional daily exercise (grid-climbing and swimming) on the fatigue and metabolic profiles of muscles from TTX-rec and control animals were investigated. The activities of citrate synthase (CS), phosphofructokinase (PFK), and alpha-glycerophosphate dehydrogenase (alpha-GPD) were depressed following 28 days of inactivity produced by the chronic neural application of TTX. The response of these muscles to a pattern of stimulation that has been used to classify fast-twitch motor units according to their fatigability (6) (330 ms, 40 Hz, l/s, 4 min) was not affected to any great extent by inactivity, except for a loss in the ability to summate or maintain forces during each 330-ms burst, as fatigue developed. After 28 days of recovery, the concentration of CS had returned to normal, whereas the concentrations of PFK and alpha-GPD remained depressed. TTX-rec muscles, on the other hand, appeared more resistant to fatigue than control muscles, based on several indices of muscle fatigue. Control and TTX muscles responded similarly to daily training. Swimming but not climbing increased the activity of CS and the fatigue resistance of the muscle. Neither exercise influenced the activity of PFK and alpha-GPD. Although the activity of CS was influenced by the level of neuromuscular usage, the former did not appear to play a dominant role in determining the fatigue resistance of the muscle, emphasizing the need to consider other factors as primary determinants of muscle fatigue.
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PMID:Recovery of muscle from tetrodotoxin-induced disuse and the influence of daily exercise. 2. Muscle enzymes and fatigue characteristics. 297 Sep 77

Effects of spinal cord transection in 2-wk-old cats on the metabolic, histochemical, and fatigue properties of a fast- and a slow-twitch muscle were determined. Chronic (6-12 mo) spinalization (Sp) resulted in an increased ratio of fast-twitch, oxidative-glycolytic (FOG) to slow-twitch, oxidative (SO) fibers in soleus (SOL). In medial gastrocnemius (MG), Sp produced a histochemical profile suggesting that fast fibers were increased at the expense of slow fibers. Changes in biochemical markers for oxidative (citrate synthase) and glycolytic (GPD) potential were consistent with the histochemical findings. The fatigue index of Sp MG and SOL remained normal and was consistent with the type and degree of fiber type change. Daily treadmill exercise did not markedly alter any of the adaptations. The metabolic and fatigue properties of skeletal muscle of Sp cats are consistent with the view that as some fibers develop "faster-like" characteristics, the oxidative and the glycolytic potential is also enhanced. As was true of the contractile properties and related biochemical data, the changes observed suggest that significant changes occurred within as well as across fiber types. These data, in conjunction with that of chronic EMG recordings, provide evidence that there is a relative independence of both the oxidative potential and the fatigability of a muscle relative to its quantity of activation.
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PMID:Relative independence of metabolic enzymes and neuromuscular activity. 673 19