The Structural and Functional Characteristics of Rat Soleus Endplates under Short-Term Disruption of Motor Activity

Abstract—In this study we analyzed the distribution of nicotinic acetylcholine receptors, the degree of their fragmentation, endplate area, and membrane localization of the α2 isoform of the Na,K–ATPase in the rat soleus muscle after functional unloading (via the method of hindlimb suspension) for 1–3 days. After unloading increased endplate fragmentation accompanied by a decrease in the area of individual fragments was observed; the total area of the endplates did not change. The density of distribution of nicotinic acetylcholine receptors also remained unaltered; however, the density of the distribution of the α2 isoform of the Na,K–ATPase significantly decreased. Presumably, these changes resulted from adaptive skeletal muscle remodeling, which develops not only during chronic disorders, but even in the early stages of motor dysfunction.