Plantar stimulation prevents the decrease in fatigue resistance in rat soleus muscle under one week of hindlimb suspension.

ABSTRACT

Support afferentation in recent years was shown to be a key physiological stimulus controlling postural muscle function, structure and phenotype. Lack of support afferentation under various types of muscle disuse leads to a decline of size and percentage of slow-type fatigue-resistant muscle fibers, which can negatively affect muscle performance and life quality. In this study we simulated support afferentation during rat hindlimb unloading and investigated its effect on postural soleus muscle functional properties and signaling. Plantar mechanical stimulation prevented the unloading-induced muscle fatigue increase, maintained the level of mitochondrial DNA copy number and the percent of slow-type muscle fibers and partially prevented the increase of CpG methylation in pgc 1α promoter region and decline in myonuclear content of several transcriptional activators of slow myosin and PGC1 α expression. So, support afferentation under hindlimb suspension leads to maintaining of a slow-twitch oxidative and fatigue-resistant soleus muscle fibers phenotype.