A Modular Visual Model of Energy Metabolism in Human Skeletal Muscle

The paper presents a modification of a multi-compartmental mathematical model describing the dynamics of intracellular species concentrations and fluxes in human muscle at rest. A modular representation of a complex model is proposed, which provides the possibility of rapid expansion and modification of the model compartments to account for the complex organization of muscle cells and the limitations of the rate of diffusion of metabolites between intracellular compartments. To illustrate the work of the model, intracellular response in human skeletal muscle to acute aerobic two-legged cycle ergometer training was considered. The model in SBML format is available at http://wiki.biouml.org/index.php/Muscle_metabolism.

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Effect of endurance exercise on myosin heavy chain gene regulation in human skeletal muscle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1999.276.2.r414 ◽

1999 ◽

Vol 276 (2) ◽

pp. R414-R419 ◽

Cited By ~ 5

Author(s):

D. Sean O’Neill ◽

Donghai Zheng ◽

Wade K. Anderson ◽

G. Lynis Dohm ◽

Joseph A. Houmard

Keyword(s):

Skeletal Muscle ◽

Myosin Heavy Chain ◽

Heavy Chain ◽

Human Skeletal Muscle ◽

Contractile Activity ◽

Maximal Oxygen Consumption ◽

Exercise Bout ◽

Cycle Ergometer ◽

Chain Gene ◽

Exercise Period

The purpose of this study was to determine the effect of endurance-oriented exercise on myosin heavy chain (MHC) isoform regulation in human skeletal muscle. Exercise consisted of 1 h of cycle ergometer work per day at 75% maximal oxygen consumption for seven consecutive days. Muscle was obtained before the first bout of exercise, 3 h after the first bout of exercise, and before and 3 h after the final exercise bout on day 7( n = 9 subjects). No changes in MHC mRNA (I, IIa, IIx) were evident after the first exercise period. There was, however, a significant ( P < 0.05) decline (−30%) in MHC IIx mRNA 3 h after the final training bout. An interesting finding was that a higher pretraining level of MHC IIx mRNA was associated with a greater decline in the transcript before ( r = 0.68, P < 0.05) and 3 h after ( r = 0.82, P < 0.05) the final exercise bout. These findings suggest that MHC IIx mRNA is downregulated during the early phase of endurance-oriented exercise training in human skeletal muscle but only after repeated contractile activity. Pretraining MHC IIx mRNA content may influence the magnitude of this response.

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Performance and fibre characteristics of human skeletal muscle during short sprint training and detraining on a cycle ergometer

European Journal of Applied Physiology ◽

10.1007/s004210050194 ◽

1997 ◽

Vol 75 (6) ◽

pp. 491-498 ◽

Cited By ~ 21

Author(s):

M.-T. Linossier ◽

D. Dormois ◽

A. Geyssant ◽

C. Denis

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Cycle Ergometer ◽

Sprint Training ◽

Fibre Characteristics ◽

Training And Detraining

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Influence of sprint training on human skeletal muscle purine nucleotide metabolism

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.4.1802 ◽

1994 ◽

Vol 76 (4) ◽

pp. 1802-1809 ◽

Cited By ~ 109

Author(s):

C. G. Stathis ◽

M. A. Febbraio ◽

M. F. Carey ◽

R. J. Snow

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Adenine Nucleotide ◽

Cycle Ergometer ◽

Nucleotide Metabolism ◽

Atp Depletion ◽

Purine Nucleotide ◽

Sprint Training ◽

Similar Reduction ◽

Purine Nucleotide Metabolism

To examine the effect of sprint training on human skeletal muscle purine nucleotide metabolism, eight active untrained subjects completed a maximal 30-s sprint bout on a cycle ergometer before and after 7 wk of sprint training. Resting muscle ATP and total adenine nucleotide content were reduced (P < 0.05) by 19 and 18%, respectively, after training. Training resulted in a 52% attenuation (P < 0.05) in the magnitude of ATP depletion after exercise and a similar reduction (P < 0.05) in the accumulation of inosine 5′-monophosphate and ammonia. During recovery, muscle inosine 5′-monophosphate (P < 0.05) and inosine (P < 0.01) content were reduced after training, as was the accumulation of inosine (P < 0.05). Plasma ammonia was higher (P < 0.05) after training early in recovery; in contrast, plasma hypoxanthine concentrations were reduced (P < 0.05) during the latter stages of recovery. The attenuated resting ATP and total adenine nucleotide contents after training probably result from the acute effects of prior training sessions. The reduction in the magnitude of ATP depletion during a 30-s sprint bout after training must reflect an improved balance between ATP hydrolysis and resynthesis. It is unclear which mechanism(s) is responsible for the reduction in the magnitude of ATP degradation after training.

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Effects of exercise on GLUT-4 and glycogenin gene expression in human skeletal muscle

Journal of Applied Physiology ◽

10.1152/jappl.2000.88.2.794 ◽

2000 ◽

Vol 88 (2) ◽

pp. 794-796 ◽

Cited By ~ 77

Author(s):

Yorgos Kraniou ◽

David Cameron-Smith ◽

Marie Misso ◽

Greg Collier ◽

Mark Hargreaves

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Oxygen Consumption ◽

Human Skeletal Muscle ◽

Glycogen Synthesis ◽

Cycle Ergometer ◽

Peak Oxygen Consumption ◽

Hexokinase Ii ◽

Glut 4 ◽

Single Bout

To investigate the effect of exercise on GLUT-4, hexokinase, and glycogenin gene expression in human skeletal muscle, 10 untrained subjects (6 women and 4 men, 21.4 ± 1.2 yr, 66.3 ± 5.0 kg, peak oxygen consumption = 2.30 ± 0.19 l/min) exercised for 60 min on a cycle ergometer at a power output requiring 73 ± 4% peak oxygen consumption. Muscle samples were obtained by needle biopsy before, immediately after, and 3 h after exercise. Gene expression was quantified, relative to 29S ribosomal protein cDNA, by RT-PCR. GLUT-4 gene expression was increased immediately after exercise (1.7 ± 0.4 vs. 0.9 ± 0.3 arbitrary units; P < 0.05) and remained significantly higher than baseline 3 h after the end of exercise (2.2 ± 0.4 vs. 0.9 ± 0.3 arbitrary units; P < 0.05). Hexokinase II gene expression was significantly higher than the resting value 3 h after the end of exercise (2.9 ± 0.4 vs. 1.3 ± 0.3 arbitrary units; P < 0.05). Exercise increased glycogenin mRNA more than twofold (2.8 ± 0.6 vs. 1.2 ± 0.2 arbitrary units; P < 0.05) 3 h after the end of exercise. For the first time, we report that a single bout of exercise is sufficient to cause upregulation of GLUT-4 and glycogenin gene expression in human skeletal muscle. Whether these increases, together with the associated increase in hexokinase II gene expression, lead to increased expression of these key proteins in skeletal muscle and contribute to the enhanced skeletal muscle glucose uptake, glycogen synthesis, and insulin action observed following exercise remains to be determined.

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Seven days of exercise increase GLUT-4 protein content in human skeletal muscle

Journal of Applied Physiology ◽

10.1152/jappl.1995.79.6.1936 ◽

1995 ◽

Vol 79 (6) ◽

pp. 1936-1938 ◽

Cited By ~ 58

Author(s):

J. A. Houmard ◽

M. S. Hickey ◽

G. L. Tyndall ◽

K. E. Gavigan ◽

G. L. Dohm

Keyword(s):

Skeletal Muscle ◽

Exercise Training ◽

Protein Content ◽

Human Skeletal Muscle ◽

Glucose Transporter ◽

Vastus Lateralis ◽

Cycle Ergometer ◽

Maximal Heart Rate ◽

Short Term ◽

Glut 4

Insulin-responsive glucose transporter (GLUT-4) content increases by 1.8-fold in skeletal muscle with 14 wk of exercise training [Houmard et al. Am. J. Physiol. 264 (Endocrinol. Metab. 27): E896-E901, 1993]. The purpose of this study was to determine whether more short-term training (7 days) increases GLUT-4 protein content in human skeletal muscle. Seven sedentary men [25.0 +/- 1.1 (SE) yr, 44.1 +/- 2.2 ml.kg-1.min-1 maximal O2 uptake, 14.9 +/- 2.1% body fat] were examined before and after 7 days of cycle ergometer training (1 h/day, 76 +/- 2% maximal heart rate). Needle biopsy samples from the vastus lateralis were used to determine GLUT-4 protein content. Muscle GLUT-4 increased (P < 0.05) by an average of 2.8 +/- 0.5-fold with 7 days of training. GLUT-4 content in skeletal muscle thus increases substantially with short-term exercise training.

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