Pools of Amino Acids of Skeletal Muscle in Yakutian Ground Squirrel Urocitellus undulatus during Different Hibernation Stages

Muscular atrophy is not observed in hibernating animals during hibernation. The mechanisms of this phenomenon are unknown, however their fine regulation should be reflected in the status of free amino acids of skeletal muscles. In this study, the composition of free amino acids in skeletal muscles of the Yakut ground squirrel in winter hibernation at 0°C was explored. There was an increase in the content of alanine during hibernation that returned to the summer level during short-term awakening. Aspartic acid was found in the skeletal muscles of ground squirrels at the beginning of torpor, and it disappeared upon short-term awakening. The pools of glycine and taurine did not change at the beginning or the end of torpor. Pools of essential amino acids increased at the end of torpor, and with a short-term awakening they return to the initial level. The interrelated increase and decrease in the content of free amino acids indicated the absence of predominance of catabolism processes over anabolism.