Conduction velocity in nerve fibres with axonal atrophy due to chronic β,β′-iminodiproprionitrile (IDPN)

Serial measurements of maximal motor nerve conduction velocity and muscle action potential amplitude were made on 2 groups of rats for up to 16 months. Group A received 0.05% IDPN in drinking water. Group B received a single injection of 1 g/kg i.p. In the chronically intoxicated animals conduction velocity progressively fell compared with control animals, from a reduction of 7% after 4 months to 22% after 13 months. There was no reduction in muscle action potential amplitude. Marked axonal atrophy was found in distal ventral roots. Many grossly dilated axons were present in proximal ventral roots. In the animals which received a single dose of IDPN no electrophysiological changes were found. A few dilated axons were present in proximal ventral roots. but changes were less severe than in Group A. No distal axonal atrophy was demonstrated.