BioProject

This study assessed the effects of weekly disuse (dry immersion; 10 males) on the strength and aerobic performance of the ankle plantar flexors and knee extensors, mitochondrial function in permeabilized muscle fibers, and the proteomic (quantitative mass spectrometry-based analysis) and transcriptomic (RNA-sequencing) profiles of the soleus muscle and vastus lateralis muscle. More...

This study assessed the effects of weekly disuse (dry immersion; 10 males) on the strength and aerobic performance of the ankle plantar flexors and knee extensors, mitochondrial function in permeabilized muscle fibers, and the proteomic (quantitative mass spectrometry-based analysis) and transcriptomic (RNA-sequencing) profiles of the soleus muscle and vastus lateralis muscle. Dry immersion-induced decreases in maximal voluntary contraction in both muscles were comparable and occurred without a decrease in the relative content of contractile proteins, which appears to be due to disruption of neuromuscular mechanisms rather than a decrease in muscle mass. The decrease in maximum ADP-stimulated mitochondrial respiration was also comparable in both muscles and occurred without a decrease in the relative content of mitochondrial proteins/respiratory enzymes, which appears to be associated with dysregulation of respiration. Meanwhile changes in the transcriptome were significantly more pronounced (2.5–4 times, in terms of number of differentially expressed genes) in the “slow” soleus muscle than in the vastus lateralis muscle. This suggests that longer-term disuse will lead to a change (primarily a decrease) in the relative content of a number of highly abundant proteins in Sol and an accelerated decline in the functional capacity of the ankle plantar flexors. Overall design: Ten males participated in a 7-day dry immersion (DI, ages 25–38 years; median height 1.78 m [interquartile range 1.71–1.79 m]; body mass 70 kg [64–74 kg]; and body mass index 24 kg/m² [21–24 kg/m²]). Muscle samples were taken using a Bergstrom needle with aspiration under local anesthesia (2 ml of 2% lidocaine) from the medial part of the vastus lateralis (VL) and soleus (Sol) muscles of the left leg 14 days before and 6 days after DI (at 10:00, 3 hours after a standardized light breakfast: 5.2 g protein, 2.7 g fat, 55 g carbohydrates, 1253 kJ). Strand-specific RNA libraries were prepared using the NEBNext Ultra II RNA kit (New England Biolabs, USA) and single-end sequencing was done by a NextSeq 550 analyzer (Illumina, USA). Less...