[Effect of prolonged weightlessness on protein metabolism in rat red and white skeletal muscles]

With the aid of C14-leucine incorporation into proteins the protein synthesis in the red (m. soleus) and white (m. extensor dig. longus) skeletal muscles of flight and synchronous rats from the Cosmos-605 experiment was investigated. On the 2nd postflight day the total synthesis of proteins (as calculated per whole muscle) in the red muscle of flight rats remained unaltered. Therefore, distinct atrophy of this muscle that was seen only in flight rats can be attributed to increased degradation of proteins. On the 2nd postflight day the white muscle of both flight and synchronous rats showed moderate atrophy, not only increased protein degradation but also inhibited protein synthesis contributes to this.