Nerve stump length and cholinesterase activity in muscle and nerve

Abstract

Neural regulation of muscle cholinesterase (ChE) is well documented, although the mechanisms remain unresolved. We examined the enzyme activity changes in nerve and muscle after nerve transection, as they relate to nerve stump length and synthesis of ChE in denervated muscle. Changes in ChE activity were determined in rat skeletal muscles and sciatic nerve after nerve transection and after irreversible inhibition with paraoxon. The results showed that the decrease in enzyme activity in muscle was unrelated to the length of nerve stump. It was also shown that denervated muscle was capable of enzyme synthesis. Enzyme activity in nerve segments distal to transections decreased earlier than in denervated muscle and ChE in these samples of nerve was less sensitive to paraoxon. Although the nerve stump length and decrease in muscle enzyme activity were unrelated, the results suggest that the earlier decrease in enzyme activity in transected nerve may be related to the loss of biochemically determined muscle ChE.