ABSTRACT
The experiments of modeling hypogravity using fluorescent microscopy have shown a decrease of expression of b1 of Na +/K+-ATPase and Ca2+-ATPase subunits and the increase in the insensitivity of synthesis of a1S subunit of the L-type Ca2+-channel of the plasmatic membrane, whereas the synthesis of a2 subunit of Na+/K+-ATPase does not change. In «fast¼ muscle only observed similar for «slow¼ muscle decrease in the expression of b1 subunit without changing other parameters were studied. However, the decrease in fluorescence b1 subunit due to spread of data was not statistically significant. Thus hypogravity adversely affects the functioning primarily skeletal muscles, providing static load.
Subject(s)
Calcium Channels, L-Type/biosynthesis , Hypergravity , Muscle Fibers, Slow-Twitch/metabolism , Sarcoplasmic Reticulum Calcium-Transporting ATPases/biosynthesis , Sodium-Potassium-Exchanging ATPase/biosynthesis , Animals , Male , Microscopy, Fluorescence , Muscle Fibers, Slow-Twitch/pathology , Rats , Rats, WistarSubject(s)
Genomics , Space Flight , Spacecraft , Spinal Cord/metabolism , Animals , Lumbar Vertebrae , Male , Mice , Mice, Inbred C57BL , Time Factors , Weightlessness/adverse effectsABSTRACT
Antiorthostatic hindlimb suspension reduces resting membrane potential of rat fast and slow muscles within 7 days. Changes in Na+/K+ pump activity and shifts of the equilibrium potential for chloride ions are the main mechanism of the changes in the resting potential of muscle fibers. The latter is presumably associated with increased intracellular ion current due to activation of the second active Na+, K+, 2Cl- symport. Reduction of the membrane potential is related to muscle denervation. However, membrane depolarization of muscle fibers during antiorthostatic suspension cannot be explained solely by changes in the mechanisms of neurotrophic control from motor neurons.
