CHANGES OF MECHANICAL PROPERTIES AND MYOSIN PHENOTYPE OF POSTURAL AND LOCOMOTOR MUSCLES AFTER 21-DAY MOTOR CONSTRAINT

Abstract

Active mechanical properties of postural and locomotor muscles were investigated in Wistar rats after 21-d motor constraint in small cages. Muscles Soleus and EDL of the right leg were tested mechanically ex vivo; RNA obtained from the left legs was used to determine concentrations of various type myosin. Motor constraint caused a significant degradation of active mechanical properties (peak strength of tetanic contraction and intensity) and reliable mass loss in both muscles. Enhanced expression of myosin IIa, IIb and IId/x was revealed in m. soleus only. Also, motor constraint affected functional properties of equally fast and slow muscles. We anticipate that further investigations will shed light on the molecular mechanisms underlying degradation of the skeletal muscles activity.