[Dehydrogenase activity in skeletal muscles of rats after long-term exposure to weightlessness]

Malate- and isocytratedehydrogenase activity in mitochondrial and cytoplasmic fractions and lactate dehydrogenase activity in hindlimb muscles have been studied at different stages after 18.5-day flight on a biosatellite "Cosmos-1129" and after 20-day hypokinesia. A decrease in dehydrogenase activity has been found on the first postflight day. The enzyme activities returned to the control values in mitochondria, and in the cytoplasm they were greater by day 6 postflight. It was concluded that hypokinesia did not reveal all the effects of microgravity on the whole system but some enzyme alterations in the muscle resembled those observed during the flight. The effects may be caused by the inhibition of both aerobic and anaerobic metabolic pathways under the effect of microgravity.