Universität zu Köln

Thot, Georgina K., Berwanger, Carolin, Mulder, Edwin, Lee, Jessica K., Lichterfeld, Yannick, Ganse, Bergita, Giakoumaki, Ifigeneia, Degens, Hans, Duran, Ibrahim ORCID: 0000-0003-4044-8822, Schoenau, Eckhard, Clemen, Christoph S., Brachvogel, Bent and Rittweger, Jorn (2021). Effects of long-term immobilisation on endomysium of the soleus muscle in humans. Exp. Physiol., 106 (10). S. 2038 - 2046. HOBOKEN: WILEY. ISSN 1469-445X

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Abstract

New Findings What is the central question of this study? While muscle fibre atrophy in response to immobilisation has been extensively examined, intramuscular connective tissue, particularly endomysium, has been largely neglected: does endomysium content of the soleus muscle increase during bed rest? What is the main finding and its importance? Absolute endomysium content did not change, and previous studies reporting an increase are explicable by muscle fibre atrophy. It must be expected that even a relative connective tissue accumulation will lead to an increase in muscle stiffness. Muscle fibres atrophy during conditions of disuse. Whilst animal data suggest an increase in endomysium content with disuse, that information is not available for humans. We hypothesised that endomysium content increases during immobilisation. To test this hypothesis, biopsy samples of the soleus muscle obtained from 21 volunteers who underwent 60 days of bed rest were analysed using immunofluorescence-labelled laminin gamma-1 to delineate individual muscle fibres as well as the endomysium space. The endomysium-to-fibre-area ratio (EFAr, as a percentage) was assessed as a measure related to stiffness, and the endomysium-to-fibre-number ratio (EFNr) was calculated to determine whether any increase in EFAr was absolute, or could be attributed to muscle fibre shrinkage. As expected, we found muscle fibre atrophy (P = 0.0031) that amounted to shrinkage by 16.6% (SD 28.2%) on day 55 of bed rest. ENAr increased on day 55 of bed rest (P < 0.001). However, when analysing EFNr, no effect of bed rest was found (P = 0.62). These results demonstrate that an increase in EFAr is likely to be a direct effect of muscle fibre atrophy. Based on the assumption that the total number of muscle fibres remains unchanged during 55 days of bed rest, this implies that the absolute amount of connective tissue in the soleus muscle remained unchanged. The increased relative endomysium content, however, could be functionally related to an increase in muscle stiffness.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Thot, Georgina K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Berwanger, Carolin UNSPECIFIED UNSPECIFIED UNSPECIFIED Mulder, Edwin UNSPECIFIED UNSPECIFIED UNSPECIFIED Lee, Jessica K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lichterfeld, Yannick UNSPECIFIED UNSPECIFIED UNSPECIFIED Ganse, Bergita UNSPECIFIED UNSPECIFIED UNSPECIFIED Giakoumaki, Ifigeneia UNSPECIFIED UNSPECIFIED UNSPECIFIED Degens, Hans UNSPECIFIED UNSPECIFIED UNSPECIFIED Duran, Ibrahim UNSPECIFIED orcid.org/0000-0003-4044-8822 UNSPECIFIED Schoenau, Eckhard UNSPECIFIED UNSPECIFIED UNSPECIFIED Clemen, Christoph S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Brachvogel, Bent UNSPECIFIED UNSPECIFIED UNSPECIFIED Rittweger, Jorn UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-593850
DOI:	10.1113/EP089734
Journal or Publication Title:	Exp. Physiol.
Volume:	106
Number:	10
Page Range:	S. 2038 - 2046
Date:	2021
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1469-445X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HUMAN QUADRICEPS MUSCLE; RAT SKELETAL-MUSCLE; COLLAGEN-SYNTHESIS; ARTIFICIAL GRAVITY; CONNECTIVE-TISSUE; BED REST; EXTRACELLULAR-MATRIX; RESISTANCE EXERCISE; PROTEIN-SYNTHESIS; SPACE Multiple languages Physiology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59385