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After humans and animals have been in conditions of real and modeled weightlessness, the most marked changes are seen in the "slow" tonic muscles, particularly soleus. Studies of the effects of weightlessness and movement restriction on the soleus muscle in monkeys demonstrated significant reductions in the sizes of slow and rapid fibers due mainly to the… (More)
The first studies of space flown rats revealed that in m.soleus (SOL) slow-twitch fibers (ST) were reduced in size more pronouncedly than fast-twitch fibers (FT). The same differences in the fiber atrophy levels were found in rats after hind-limb suspension. At the same time, the studies on humans exposed to real and simulated weightlessness demonstrated… (More)
Magnetic resonance imaging (MRI), histomorphometry and electron microscopy of muscle demonstrate that long-term exposure to actual or simulated weightlessness (including head down bed rest) leads to decreased volume of antigravity muscles in mammals. In muscles interbundle space is occupied by the connective tissue. Rat studies show that hindlimb unloading… (More)
It had been hypothesized and recently shown that the exposure to gravitational unloading brought out to sufficient accumulation of Ca2+ in the myoplasm of soleus muscle fibers. Some authors believe that this dramatic Ca2+ accumulation induces the muscle protein degradation (including cytoskeletal proteins) by means of Ca 2(+)-activated proteases. For… (More)
Effects of long duration hypergravity on m. soleus morphology characteristics are still unknown. Particularly, only one paper describes the size and myosin heavy chain profiles of rat hindlimb extensor muscle fibers after 2 weeks of +2 G exposure. Earlier it was shown that long term overloading induced changes in skeletal muscle fiber cross-sectional area… (More)
The effect of microgravity on slow- and fast-twitch fibers of m. vastus lateralis of rhesus monkeys was investigated. After real flight, fibers of both types were reduced in size, whereas after simulated flight, only type I fibers tended to diminish. Oxidative potential decreased in type II fibers of both flight and control animals.
It is known that exposure to actual or simulated weightlessness is often accompanied by decreased muscle dynamic performance, and increased level of blood lactate accumulation. Decreased mitochondrial content found in fibers of the working muscles is considered to be one of the possible causes for those changes. Studies on oxidative potential of the muscle… (More)
The purpose of the present study was to perform comprehensive hematological investigations of females in a 120-day head-down (-5 degrees) bed rest and in the period of recovery. Morphometric, cytochemical parameters of erythrocytes and lymphocytes, erythropoietic activity and turnover of iron were analyzed in 8 female subjects assigned into two groups of 4.… (More)
After staying in real and simulated weightlessness, the most obvious changes were recorded in the "slow" tonic muscles like m. soleus, the protein loss in the fibres being greater than the loss of other components, water included.