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)

Skeletal muscle glucose transport can be regulated by hormonal factors such as insulin and insulin-like growth factor I (IGF-I). Although it is well established that exercise training increases insulin action on muscle glucose transport, it is currently unknown whether exercise training leads to an enhancement of IGF-I-stimulated glucose transport in skeletal muscle. Therefore, we measured glucose transport activity [by using 2-deoxy-D-glucose glucose (2-DG) uptake] in the isolated rat epitrochlearis muscle stimulated by submaximally and maximally effective concentrations of insulin (0.2 and 13.3 nM) or IGF-I (5 and 50 nM) after 1, 2, and 3 wk of voluntary wheel running (WR). After 1 wk of WR, both submaximal and maximal insulin-stimulated 2-DG uptake rates were significantly (P < 0.05) enhanced (43 and 31%) compared with those of sedentary controls, and these variables were further increased after 2 (86 and 57%) and 3 wk (71 and 70%) of WR. Submaximal and maximal IGF-I-stimulated 2-DG uptake rates were significantly enhanced after 1 wk of WR (82 and 61%, and these increases did not expand substantially after 2 (71 and 58%) and 3 wk (96 and 70%) of WR. This enhancement of hormone-stimulated 2-DG uptake in WR muscles preceded any alteration in glucose transporter (GLUT-4) protein level, which increased only after 2 (24%) and 3 wk (54%) of WR. Increases in GLUT-4 protein were significantly correlated (r = 0.844) with increases in citrate synthase. These results indicate that exercise training can enhance both insulin-stimulated and IGF-I-stimulated muscle glucose transport activity and that these improvements can develop without an increase in GLUT-4 protein.
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PMID:Voluntary exercise training enhances glucose transport in muscle stimulated by insulin-like growth factor I. 904 30

The present study investigated whether recombinant human (rh) growth hormone (GH) combined with endurance training would have a larger effect on oxidative capacity, metabolism, and body fat than endurance training alone. Sixteen healthy, elderly women, aged 75 yr, performed closely monitored endurance training on a cycle ergometer over 12 wk. rhGH was given in a randomized, double-blinded, placebo-controlled design in addition to the training program. GH administration resulted in a doubling of serum insulin-like growth factor I levels. With endurance training, peak oxygen uptake increased by approximately 18% in both groups, whereas the marked increase in muscle citrate synthase activity was 50% larger in the GH group compared with the placebo group. In addition, only the GH group revealed an increase in muscle L-3-hydroxyacyl-CoA dehydrogenase activity. Body weight remained unchanged in both groups, but the GH group showed significant changes in body composition with a decrease in fat mass and an increase in lean body mass. Twenty-four-hour indirect calorimetry performed in four subjects showed a marked increase in energy expenditure with increased relative and absolute fat combustion in the two subjects receiving rhGH. In conclusion, rhGH adds to the effects of endurance training on muscle oxidative enzymes and causes a reduction in body fat in elderly women.
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PMID:Growth hormone enhances effects of endurance training on oxidative muscle metabolism in elderly women. 1105 52