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.

Download full-text PDF

Source
http://dx.doi.org/10.1113/EP089734DOI Listing

Publication Analysis

Top Keywords

muscle fibre
16
endomysium content
16
soleus muscle
12
fibre atrophy
12
bed rest
12
muscle
10
connective tissue
8
muscle fibres
8
day bed
8
endomysium
7

Similar Publications

Introduction: Skeletal muscle satellite cells (MuSCs or stem cells) play a crucial role in muscle development, maintenance, and regeneration, supporting both hypertrophy and regenerative myogenesis. Syndecans (SDCs) act as communication bridges within the muscle microenvironment, regulating interactions with extracellular matrix components and contributing significantly to tissue repair and inflammation. Specifically, syndecan-4 (SDC4) is involved in muscle regeneration at multiple stages.

View Article and Find Full Text PDF

The pectoralis muscle in birds is important for flight and thermogenesis. In migratory songbirds this muscle exhibits seasonal flexibility in size, but whether this flexibility reflects changes in muscle fiber type has not been well documented. We investigated how seasonal changes in photoperiod affected pectoralis muscle fiber type and metabolic enzymes, comparing among three closely-related sparrow species: two seasonal migrants and one year-round, temperate climate resident.

View Article and Find Full Text PDF

The increasing demand for protein-rich, plant-based foods has driven the development of meat analogs that closely mimic the texture and mouthfeel of animal meat. While plant-based fibrils and electrospun silk fibroin fibers have been explored for texture enhancement and scaffolding in both meat analogs and cell-based meats, the use of wet-spun fibroin protein fibers as a food ingredient remains underexplored. This study investigates the potential of wet-spun recombinant fibroin fibers to enhance the textural properties of meat analogs.

View Article and Find Full Text PDF

Hydroxycinnamic acid derivatives are a class of phenolic acid compounds, including sinapic acid, ferulic acid, and caffeic acid, which are widely found in plants. This experiment was conducted to study the effects of hydroxycinnamic acid derivatives (sinapic acid, ferulic acid, and caffeic acid) on the growth performance, muscle physical parameters, and intestinal morphology of tilapia. A total of 320 tilapia fingerlings (9.

View Article and Find Full Text PDF

Introduction: Excess weight during pregnancy is a condition that can affect both mother and fetus, through the maternal-fetal interface, which is constituted by the placenta and umbilical cord. The umbilical vein is responsible for transporting oxygen and nutrients to the fetus, and its proper functioning depends on the integrity of its structure. The remodeling of the umbilical vein represents one of the causes of inadequate transport of nutrients to the fetus, being potentially harmful.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!