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Folkesson, Mattias
Publications (3 of 3) Show all publications
Tarum, J., Folkesson, M., Atherton, P. J. & Kadi, F. (2017). Electrical pulse stimulation: an in vitro exercise model for the induction of human skeletal muscle cell hypertrophy. A proof-of-concept study. Experimental Physiology, 102(11), 1405-1413.
Open this publication in new window or tab >>Electrical pulse stimulation: an in vitro exercise model for the induction of human skeletal muscle cell hypertrophy. A proof-of-concept study
2017 (English)In: Experimental Physiology, ISSN 0958-0670, E-ISSN 1469-445X, Vol. 102, no 11, p. 1405-1413Article in journal (Refereed) Published
Abstract [en]

New Findings:

  • What is the central question of this study?

Is electrical pulse stimulation (EPS) an in vitro exercise model able to elicit the hypertrophy of human muscle cells?

  • What is the main finding and its importance?

The addition of a restitution period of 8h after EPS induces the enlargement of human muscle cells, a major physiological end-point to resistance exercise. This is supported by downregulationof myostatin, a negative regulator of muscle mass, and increased phosphorylated mTOR and 4E-BP1, key factors in the growth cascade. This proof-of-concept study provides a model of physiologically mediated muscle growth, which will be the basis for future studies aiming to depict molecular events governing the hypertrophy of human muscle cells.

Electrical pulse stimulation (EPS) of muscle cells has previouslybeenused as an in vitro exercise model. The present study aimedto establish an EPS protocol promoting the hypertrophy ofhuman muscle cells, which represents a major physiological end-point to resistance exercise in humans. We hypothesized that adding a resting period after EPS would be crucial for the occurrence of the morphological change. Myoblasts obtained from human muscle biopsies (n=5) were differentiated into multinucleated myotubes and exposed to 8h of EPS consisting of 2ms pulses at 12V, with a frequency of 1Hz. Myotube size was assessed using immunohistochemistry immediately, 4 and 8h after completed EPS. Gene expression and phosphorylation status of selected markers of hypertrophy were assessed using RT-PCR and Western blotting, respectively. Release of the myokine interleukin-6 in culture medium was measured using enzyme-linked immunosorbent assay. We demonstrated a significant increase (31 +/- 14%; P=0.03) in the size of myotubes when EPS was followed by an 8h resting period, but not immediately or 4h after completion of EPS. The response was supported by downregulation (P=0.04) of the gene expression of myostatin, a negative regulator of muscle mass, and an increase in phosphorylated mTOR (P=0.03) and 4E-BP1 (P=0.01), which are important factors in the cellular growth signalling cascade. The present work demonstrates that EPS is an in vitro exercise model promoting the hypertrophy of human muscle cells, recapitulating a major physiological end-point to resistance exercise in human skeletal muscle.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keyword
Cell growth, muscle contraction, myotube morphology
National Category
Physiology
Identifiers
urn:nbn:se:oru:diva-61685 (URN)10.1113/EP086581 (DOI)000414175100010 ()28861930 (PubMedID)2-s2.0-85032974682 (Scopus ID)
Available from: 2017-11-14 Created: 2017-11-14 Last updated: 2018-01-13Bibliographically approved
Folkesson, M., Mackey, A. L., Langberg, H., Oskarsson, E., Piehl-Aulin, K., Henriksson, J. & Kadi, F. (2013). The expression of heat shock protein in human skeletal muscle: effects of muscle fibre phenotype and trainingbackground. Acta Physiologica, 209(1), 26-33.
Open this publication in new window or tab >>The expression of heat shock protein in human skeletal muscle: effects of muscle fibre phenotype and trainingbackground
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2013 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 209, no 1, p. 26-33Article in journal (Refereed) Published
Abstract [en]

Aim

Exercise-induced adaptations of skeletal muscle are related to training mode and can be muscle fibre type specific. This study aimed to investigate heat shock protein expression in type I and type II muscle fibres in resting skeletal muscle of subjects with different training backgrounds.

Methods

Three groups of subjects were included: healthy active not engaged in any training programme (ACT, n = 12), resistance trained (RES, n = 6) and endurance trained (END, n = 8). Biopsies were obtained from vastus lateralis, and immunohistochemistry was performed using monoclonal antibodies against myosin heavy chain I and IIA, αB-crystallin, HSP27, HSP60 and HSP70.

Results

In ACT and RES, but not in END, a fibre type–specific expression with higher staining intensity in type I than type II fibres was seen for αB-crystallin. The opposite (II > I) was found for HSP27 in subjects from ACT (6 of 12 subjects) and RES (3 of 6), whereas all subjects from END displayed uniform staining. HSP60 showed no fibre-specific expression. HSP70 displayed a fibre-specific expression pattern (I > II) in ACT (4 of 12), but not in END or RES.

Conclusion

This study shows that the level of expression of the different HSPs in human skeletal muscle is influenced by muscle fibre phenotype. The fibre type–specific expression of HSP70 is influenced by resistance and endurance training, whereas those of αB-crystallin and HSP27 is influenced only by endurance training, suggesting the existence of a training-modality-specific action on the adaptive processes including heat shock proteins in human skeletal muscle.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013
Keyword
adaptation; adaptation; endurance; heat shock protein; immunohistochemistry; resistance
National Category
Sport and Fitness Sciences
Research subject
Sports Physiology/Medicine
Identifiers
urn:nbn:se:oru:diva-30127 (URN)10.1111/apha.12124 (DOI)000322950400006 ()23710799 (PubMedID)2-s2.0-84881557932 (Scopus ID)
Note

Funding agency:

Nordea Foundation

Available from: 2013-08-06 Created: 2013-08-06 Last updated: 2017-12-06Bibliographically approved
Folkesson, M., Mackey, A. L., Holm, L., Kjaer, M., Paulsen, G., Raastad, T., . . . Kadi, F. (2008). Immunohistochemical changes in the expression of HSP27 in exercised human vastus lateralis muscle. Acta Physiologica, 194(3), 215-222.
Open this publication in new window or tab >>Immunohistochemical changes in the expression of HSP27 in exercised human vastus lateralis muscle
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2008 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 194, no 3, p. 215-222Article in journal (Refereed) Published
Abstract [en]

AIM: The role of HSP27 in the adaptive process of skeletal muscle to exercise, especially in humans, is not well understood. The objective of this study was to investigate immunohistochemical changes in HSP27 expression in human vastus lateralis muscle following resistance and endurance exercises.

METHODS: Two different exercise protocols were used: (1) one-leg ergometer cycling (EC, n = 6) consisting of two 30-min bouts at 40% and 75% of peak oxygen uptake, respectively, and (2) leg extension resistance exercise (RE, n = 9) including 10 sets of eight repetitions at a load corresponding to 70% of one maximal repetition (1RM). Immunohistochemistry using specific monoclonal antibodies was used to determine the location of HSP27 protein in muscle biopsies from human vastus lateralis.

RESULTS: Our results show that RE, but not EC, induced a significant appearance of scattered accumulations of HSP27 protein in muscle fibres from five of nine subjects. The number of fibres with accumulation of HSP27 in RE ranged from 0% to 32% with a mean of 6.3% of the total number of fibres.

CONCLUSION: We conclude that this rapid HSP27 protein relocation after RE is an important player in the cellular remodelling of human muscle fibres in response to exercise involving high-force contractions, but not in response to endurance exercises.

National Category
Medical and Health Sciences Physiology
Research subject
Physiology
Identifiers
urn:nbn:se:oru:diva-4751 (URN)10.1111/j.1748-1716.2008.01875.x (DOI)18489727 (PubMedID)
Available from: 2008-11-24 Created: 2008-11-24 Last updated: 2018-01-13Bibliographically approved
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