ADAPTIVE RESPONSES OF TRPC1 AND TRPC3 DURING SKELETAL MUSCLE ATROPHY AND REGROWTH

Introduction: We assessed the time-dependent changes of transient receptor potential canonical type 1 (TRPC1) and TRPC3 expression and localization associated with muscle atrophy and regrowth in vivo. Methods: Mice were subjected to hindlimb unloading for 7 or 14 days (7U, 14U) followed by 3, 7, or 14 days of reloading (3R, 7R, 14R). Results: Soleus muscle mass and tetanic force were reduced significantly at 7U and 14U and recovered by 14R. Recovery of muscle fiber cross-sectional area was observed by 28R. TRPC1 mRNA was unaltered during the unloading-reloading period. However, protein expression remained depressed through 14R. Decreased localization of TRPC1 to the sarcolemma was observed. TRPC3 mRNA and protein expression levels were decreased significantly during the early phase of reloading. Conclusions: Given the known role of these channels in muscle development, changes observed in TRPC1 and TRPC3 may relate closely to muscle atrophy and remodeling processes. Muscle Nerve49: 691-699, 2014