LDH isoenzymes of skeletal muscles of rats after space flight and hypokinesia.

Carbohydrate metabolism of the red-soleus and mixed-plantaris muscles of rats was studied during their exposure to weightlessness and hypokinesia. With respect to the isoenzyme spectrum of LDH, it was shown that the red and mixed muscles reacted differently to the 22-d orbital flight and hypokinetic exposure. The greatest changes of the LDH spectrum in the soleus muscle were found on the 15th hypokinetic day. These changes were similar to the changes in the soleus muscle of flight rats. The most significant changes of the LDH spectrum in the plantaris muscle were detected on the 60th hypokinetic day. No differences were found in the LDH spectrum of the plantaris muscle between the flight and control animals. Our study gives evidence that disturbances in carbohydrate metabolism play a major role in atrophic and dystrophic developments in skeletal muscles during a reduced functional load on them.