[Metabolic processes in rat skeletal muscle after a flight on the Kosmos-936 biosatellite]. / Sostoianie protsessov metabolizma v skeletnykh myshtsakh krys posle poleta na biosputnike "Kosmos-936".

The study of skeletal muscles of rats flown on Cosmos-936 demonstrated different metabolic reactions in muscle fibers of different function and type to weightlessness and Earth gravity. The data obtained gave evidence that artificial gravity may considerably prevent metabolic changes in muscles developing in response to specific effects of weightlessness.

[Enzyme activity of carbohydrate metabolism in rat skeletal muscle after space flight]. / Aktivnost' nekotorykh fermentov obmena uglevodov v skeletnykh myshtsakh krys posle kosmicheskogo poleta.

Space flight factors did not influence activity of glycogen phosphorylase and adenylate cyclase in skeletal muscles of rats. Activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases increased noticeably in the most active muscles (gastrocnemius and tibialis anterior muscles). Activation of enzymes involved in the pentosephosphate pathway of glucose conversion may be associated with compensatory processes induced by muscle changes due to diminished motor activity of animals in space flight.

[Protein fractions and their enzyme activity in the rat myocardium in a Kosmos-936 biosatellite experiment]. / Belkovye fraktsii i ikh fermentativnaia aktivnost' v miokarde krys v éksperimente na biosputnike "Kosmos-936".

The effect of artificial gravity on protein fractions and their enzyme activity in the myocardium of rats flown on board Cosmos-936 was studied. In weightless rats the content of sarcoplasmic proteins increased at R + O and that of T fraction proteins decreased at R + 25. In centrifuged rats such changes were not seen. In centrifuged rats the enzyme activity of sarcoplasmic proteins did not alter. In weightless rats ATPase activity of myosin decreased significantly, and in centrifuged rats it remained almost unchanged.

[Changes in the soleus muscle tissue metabolism of rats after a flight on the Kosmos-690 biosatellite]. / Izmeneniia metabolizma tkani kambalovidnoi myshtsy u krys posle poleta na biosputnike "Kosmos-690".

The soleus muscle of flown rats did not show any effect of gamma-irradiation on the composition and enzymic activity of protein fractions. On the Ist postflight day a significant decrease in the content of myofibrillar and sarcoplasmatic proteins in the soleus muscle was found. Besides, a drastic increase in the activity of aspartate aminotransferase and lactate dehydrogenase of sarcoplasmatic proteins and an atrophic type change in the LDH pattern were demonstrated. Those changes were similar to the weighttlessness-induced processes of atrophy and dystrophy and proved reversible.

[Protein fractions and their enzymatic activity in the rat myocardium after a flight on the Cosmos-690 biosatellite]. / Belkovye fraktsii i ikh fermentativnaia akivnost' v miokarde krys posle poleta na biosputnike "Kosmos-690".

Gamma-irradiation of rats in the ground-based experiment decreased the activity of aspartate aminotransferase of sarcoplasmatic proteins of the myocardium and increased the activity of adenosine triphosphate of myosin of the myocardium 1 and 26 days post-test. Gamma-irradiation of flight rats also reduced the activity of aspartate aminotransferase of sarcoplasmatic proteins of the myocardium; however, the activity of ATPase of myosin of the myocardium was lowered both 1 and 26 days postflight. It is suggested that irradiation-induced inhibition of synthetic processes delayed the synthesis of myosin with a normal activity and diminished the protein content in the T fraction of myocardium on the 1st postflight day.

[Effect of space flight and of the accompanying radiation on amino acid metabolism in the skeletal muscle of rats]. / Vliianie kosmicheskogo poleta i soputstvuiushchei radiatsii na aminokislotnyi obmen v skeletnoi myshtse u krys.

It was demonstrated that a combined effect of 20.5-day space flight and gamma-irradiation reduced the content of biologically important amino acids (methionine, phenylalanine, serine, aspartic and glutamic acids) and inhibited the activity of aspartate aminotransferase of sarcoplasmatic proteins in the quadriceps muscle of rats. Comparison of these data with the Cosmos-605 results and literature reports suggested that gamma-irradiation inhibited the synthetic processes in the skeletal muscle.

[Protein fractions and their enzyme activity in rat myocardium after a 22-hour space flight]. / Belkovye fraktsii i ikh fermentativnaia aktivnost' v miokarde krys posle 22-sutochnogo kosmicheskogo poleta

No significant changes in the content of sarcoplasmatic and myofibrillar proteins were found in the myocardium of rats that made a 22-day flight onboard the biosatellite. On the 2nd and 26th postflight days the activity of aspartate and alanine aminotransferases of sarcoplasmatic proteins was increased and the total activity of lactate dehydrogenase and its isoenzyme spectrum remained unchanged. On the 2nd postflight day the ATPase activity of myosin of the myocardium was substantially lowered and on the 26th postflight day it returned to the normal. This decline in the ATPase activity of myosin can be regarded as an adaptive reaction to weightlessness.

[Effect of a 22-day space flight on the metabolism of rat skeletal muscle tissue]. / Vliianie 22-sutochnogo kosmicheskogo poleta na metabolizm tkani skeletnykh myshts u krys

Skeletal muscles of flight rats showed no changes in the content of glycogen, adenosine triphosphatase activity of myosin and protein content in protein fractions (except the T fraction where the protein content increased on the 1st and returned to the normal on the 26th postflight day). On the 1st postflight day activities of aminotransferases and lactate dehydrogenase of sarcoplasmatic proteins were elevated and the isoenzyme spectrum of LDH was changed as if in muscular atrophy. The amount of free amino acids in muscles was lowered. On the 26 the postflight day the enzymic activity of sarcoplasmatic proteins remained increased whereas the isoenzyme spectrum of LDH returned to the normal and the amount of free amino acids grew significantly. In the microsomal fraction of muscles the phospholipid content decreased on the 1st and returned to the normal on the 26th postflight day.