Velocity and intensity of bidirectional migration of acetylcholinesterase in transected nerves

Abstract

Migration of AChE was studied in transected nerves of dogs. The amount of enzyme accumulating near the cut ends under various experimental conditions was used to determine the characteristics of axonal transport of AChE. This transport is bidirectional. Its velocity is 260 mm/day in the proximo-distal, and 134 mm/day in the disto-proximal direction. The polarity is not directly dependent on connections with cell bodies and is maintained in completely isolated nerve segments. Both velocities are characteristic of ‘fast’ transport. The intensity of migration is also different. The amount of AChE in unit length of nerve carried in the descending direction is about twice as large as that in the ascending direction. Only about 15% of the AChE content of the nerve moves by fast transport. The rest is either immobile or moves very slowly. It is possible that transection initially causes a slight additional mobilization of the enzyme. Similarities and differences between axonal migration in intact and transected nerves are discussed.