Effects of Electrical Stimulation on Molecular Forms of Butyrylcholinesterase in Denervated Fast and Slow Latissimus Dorsi Muscles of Newly Hatched Chicken

: The effects of denervation and direct electrical stimulation upon the activity and the molecular form distribution of butyrylcholinesterase (BuChE) were studied in fast‐twitch posterior latissimus dorsi (PLD) and in slow‐tonic anterior latissimus dorsi (ALD) muscles of newly hatched chicken. In PLD muscle, denervation performed at day 2 substantially reduced the rate of rapid decrease of BuChE specific activity which takes place during normal development, whereas in the case of ALD muscle little change was observed. Moreover, the asymmetric forms which were dramatically reduced in denervated PLD muscle were virtually absent in denervated ALD muscle at day 14. Denervated PLD and ALD muscles were stimulated from day 4 to day 14 of age. Two patterns of stimulation were applied, either 5‐Hz frequency (slow rhythm) or 40‐Hz frequency (fast rhythm). Both patterns of stimulation provided the same number of impulses per day (about 61,000). In PLD muscle, electrical stimulation almost totally prevented the postdenervation loss in asymmetric forms and led to a decrease in BuChE specific activity. In ALD muscle, electrical stimulation partially prevented the asymmetric form loss which occurs after denervation. This study emphasizes the role of evoked muscle activity in the regulation of BuChE asymmetric forms in the fast PLD muscle and the differential response of denervated slow and fast muscles to electrical stimulation.