Distinguishing unloading. Versus reloading-induced changes in rat soleus muscle
Article first published online: 13 OCT 2004
Copyright © 1993 John Wiley & Sons, Inc.
Muscle & Nerve
Volume 16, Issue 1, pages 99–108, January 1993
How to Cite
Krippendorf, B. B. and Riley, D. A. (1993), Distinguishing unloading. Versus reloading-induced changes in rat soleus muscle. Muscle Nerve, 16: 99–108. doi: 10.1002/mus.880160116
- Issue published online: 13 OCT 2004
- Article first published online: 13 OCT 2004
- Manuscript Accepted: 2 JUL 1992
- hindlimb suspension;
- skeletal muscle;
- space flight;
Previously, solei from rats orbited 12.5 days aboard Cosmos 1887 biosatellite were biopsied 48–56 hours postflight. These atrophic muscles showed severe pathology. Designing a ground-based model of that space flight, we tested the hypothesis that 48 hours of postflight muscle reloading induced pathological changes. Rats were subjected to 12.5 days of hindlimb suspension unloading and biopsied immediately after suspension or after returning to normal weightbearing 12, 24, or 48 hours. Soleus morphological changes were quantitated on histochemically and immunohistochemically stained cross-sections. Solei from 0-hour reloaded rats showed significantly decreased wet weights, diminished myofiber cross-sectional area, angular myofibers, myofiberil disruption, and more myofibers expressing fast myosin. Compared with suspension alone (0-hour reloading), reloading 12–48 hours induced slightly increased soleus wet weights, myofiber swelling, significant interstital tissue edema, macrophage activation, and monocyte infiltration. These results suggest the degree and type of muscle degenerative changes observed postflight depend on the duration of gravity readaptation before biopsy and not solely on exposure to microgravity. © 1993 John Wiley & Sons, Inc.