[Biochemical study on different situations of type 2C fiber in rats]

Type 2C fibers from the soleus, gastrocnemius and extensor digitorum longus muscles of the rats were histochemically and biochemically examined in three different conditions; muscles in the neonatal stage, after neonatal denervation and on regenerating process after bupivacaine induced injury. On histochemical examination, neonatal muscles contained 100% of type 2C muscle fibers in all muscles examined, denervated muscles 94% in soleus, 42% in gastrocnemius and 57% in extensor digitorum longus and bupivacaine treated muscles 90%, 61% and 73% of type 2C fibers, respectively. On biochemical analyses, the triglyceride was the smallest and glycogen the largest in amount in all neonatal muscles, triglyceride was the largest and glycogen low in amount in neonatally denervated muscles, both triglyceride and glycogen were low in amount in bupivacaine treated regenerating muscles. And the fatty acid compositions of triglyceride were also different in different type 2C fibers. These results suggested that though histochemical characteristics are the same, significant differences in biochemical properties are present between type 2C fibers of these three conditions in that there are the smallest amount of triglyceride and the largest amount of glycogen in denervated muscles, are both low amount of triglyceride and glycogen in regenerating fibers.