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Effects of long‐term immobilisation on endomysium of the soleus muscle in humans

Thot, Georgina K. and Berwanger, Carolin and Mulder, Edwin and Lee, Jessica K. and Lichterfeld, Yannick and Ganse, Bergita and Giakoumaki, Ifigeneia and Degens, Hans and Duran, Ibrahim and Schönau, Eckhard and Clemen, Christoph S. and Brachvogel, Bent and Rittweger, Jörn (2021) Effects of long‐term immobilisation on endomysium of the soleus muscle in humans. Experimental Physiology, 106 (10), pp. 2038-2045. Wiley. doi: 10.1113/EP08973. ISSN 0958-0670.

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Official URL: http://dx.doi.org/10.1113/EP089734

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. Abstract: 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 γ-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 URL in elib:https://elib.dlr.de/144849/
Document Type:Article
Title:Effects of long‐term immobilisation on endomysium of the soleus muscle in humans
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Thot, Georgina K.UNSPECIFIEDUNSPECIFIED
Berwanger, CarolinCarolin.Berwanger (at) dlr.deUNSPECIFIED
Mulder, EdwinEdwin.Mulder (at) dlr.deUNSPECIFIED
Lee, Jessica K.UNSPECIFIEDUNSPECIFIED
Lichterfeld, YannickYannick.Lichterfeld (at) dlr.dehttps://orcid.org/0000-0001-8755-9920
Ganse, BergitaUNSPECIFIEDUNSPECIFIED
Giakoumaki, IfigeneiaUNSPECIFIEDUNSPECIFIED
Degens, HansUNSPECIFIEDUNSPECIFIED
Duran, IbrahimUNSPECIFIEDUNSPECIFIED
Schönau, EckhardUNSPECIFIEDUNSPECIFIED
Clemen, Christoph S.Christoph.Clemen (at) dlr.dehttps://orcid.org/0000-0002-1291-4219
Brachvogel, BentUNSPECIFIEDUNSPECIFIED
Rittweger, JörnMuscle and Bone Metabolism Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany; Joern.Rittweger (at) dlr.dehttps://orcid.org/0000-0002-2223-8963
Date:24 August 2021
Journal or Publication Title:Experimental Physiology
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:106
DOI :10.1113/EP08973
Page Range:pp. 2038-2045
Publisher:Wiley
ISSN:0958-0670
Status:Published
Keywords:connective tissue; endomysium; immobilisation; muscle atrophy.
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Gravisensorics
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine > Gravitational Biology
Institute of Aerospace Medicine > Leitungsbereich ME
Institute of Aerospace Medicine > Muscle and Bone Metabolism
Deposited By: Schönenberg, Sandra
Deposited On:28 Oct 2021 16:40
Last Modified:29 Oct 2021 12:35

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