By electron microscopy ultrastructures of myofibers of the soleus and gastrocnemius muscles of rats flown in zero-g and 1 g were examined. It was found that 4.5--9 hours postflight the soleus of weightless rats showed local destruction of the contractile and mitochondrial systems accompanied by metabolic changes in muscle fibers. Exposure to artificial gravity partially prevented changes in muscle fibers. Examinations of muscle fibers 25 days postflight demonstrated that the changes were reversible. No changes were seen in the mixed -- gastrocnemius -- muscle of both animal groups.

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PubMedDate not supplied

[Myocardial ultrastructure of rats exposed aboard biosatellite "Cosmos-936"].

Hearts of rats flown for 19.5 days aboard the biosatellite. Cosmos-936 and decapitated 4.5--9 hours or 25 days postflight were examined electron microscopically. Hearts of weightless rats sacrificed at R + O showed marked and consistent changes in capillaries and venules; myelin transformation of membranes of mitochondria and sarcoplasmatic reticulum was seen in cardiomyocytes which did not show lysis. It is assumed that development of myelin bodies and increase in the number of autophagosomes in weightless rats were caused by disintegration of mitochondrial and sarcoplasmatic reticulum structures. Rats exposed inflight to artificial gravity displayed less pronounced submicroscopic changes.

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PubMedDate not supplied

[Ultrastructure of the blood vessels and muscle fibers in the skeletal muscle of rats flown on the Kosmos-605 and Kosmos-782 biosatellites].

Electron microscopy was used to study ultrastructures of the wall of blood vessels and muscle fibers of the red (soleus) and mixed (gastrocnemius) muscles of rats flown on Cosmos-605 for 22.5 days and on Cosmos-782 for 19,5 days and sacrificed 4-6 hours, 48 hours and 25-27 days postflight. It was demonstrated that the orbital flight did not induce significant changes in the ultrastructure of blood vessels of the soleus and gastrocnemius muscles but caused atrophy of muscle fibers and reduction of the number of functioning capillaries. Readaptation of the soleus vascular system to 1 g led to degradation of permeability of capillary and venular walls and development of edema of the perivascular connective tissue. This may be one of the factors responsible for dystrophic changes in muscle fibers.

Animals↗