INFLUENCE OF A DEXTRAN DERIVATIVE ON MYOSIN HEAVY-CHAIN EXPRESSION DURING RAT SKELETAL-MUSCLE REGENERATION

We recently described dextran derivatives (RGTA) which stimulate tissu e repair in several in vivo models. One of them, RGTA11, has been show n to accelerate crush-induced regeneration and reinnervation of rat ED L and Soleus muscles. In this study we wanted to know if RGTA11 alters the pattern of myosin heavy chain expression during regeneration. In both EDL and Soleus muscles, RGTA ii, injected at the moment of the cr ush, was found to accelerate the shift from neonatal to adult myosin h eavy chain isoforms within 2 weeks. The proportion of slow fibers incr eased considerably, especially in the Soleus where RGTA11 induced a pr ecocious and permanent expression of slow myosin isoform, thus confirm ing that a more efficient innervation had occurred in the presence of RGTA11. These results illustrate the interesting potential pharmacolog ical use of such dextran derivatives in neuromuscular disease.