Effect of weightlessness on myofibrillar proteins of rat skeletal muscles with different functions in experiment of biosatellite "Cosmos-1129".

The composition of contractile and regulatory proteins was studied in rat muscles with different functions. The rats were exposed to weightlessness for 18.5 days during a space journey in biosatellite Cosmos-1129. Under the effect of weightlessness the myosin light chain composition changed, the quantity of myosin LC-3 subunits increased in the soleus and extensor digitorum longus (EDL) while it decreased in the triceps and brachialis muscles. The experiments showed changes in the subunit composition of the TN-TM complex, too. The results obtained are in favour of a possible adequate transformation of fibril phenotypes of some (antigravitational) muscles under the effect of spaceflight.