Mechanisms of rodent slow-twitch skeletal muscle atrophy in response to complete inactivation by spinal-isolation

Collectively our findings clearly suggest that in the model of spinal isolation (SI) which causes rapid levels of atrophy and protein loss, there occurs 1) a marked reduction in the capacity to maintain mRNA substrate for key proteins (MHC and actin) which comprise the backbone of the muscle; 2) this occurs by decreases in transcriptional activity of the key marker genes; 3) a reduction in total RNA of which the majority is ribosomal or the prime machinery to perform protein synthesis; and 4) likely an increase in expression of enzymes involved in protein degradation. Thus these patterns are consistent with the rapid net loss is protein that occurs during the first 8 days following SI treatment and continues to about 16 days at which time the muscle reaches a new steady state of reduced/maintained muscle mass.