Comparative analysis of structural and functional characteristics of soleus muscle in rats and mongolian gerbils during gravitational unloading of different duration

A comparative investigation of the dynamics of contractile properties of the whole soleus muscle and its fibers during 3- and 12-day-long hindlimb suspension of Wistar rats and Mongolian gerbils ( Meriones unguiculatus ) has been performed. The data obtained indicate that the structural and functional changes caused by hypogravity in gerbils are slowed down compared with rats. A very intense drop in water content in gerbils was found, which can cause shifts in the ionic strength of the intracellular space of the muscle fiber. As a result, the proteolytic activity of enzymes may change, which can induce a less pronounced reduction in Z-disk and M-line stiffness and contractile capabilities in gerbils compared with rats.