PROLONGED INJURY DISCHARGE IN UNMYELINATED NERVE-FIBERS FOLLOWING TRANSECTION OF THE SURAL NERVE IN RATS

We studied the prolonged injury discharge in axotomized myelinated (A) and unmyelinated (C) nerve fibres within the first 15 min following s ural nerve transection of the rat. Immediately after axotomy, 18% (22/ 122) of the C fibres generated action potentials, but none of 73 A fib res. This discharge ceased during the first 2 min after axotomy in mos t of the C fibres. The discharge frequency in the first 15 s after ner ve cut varied between 0.3 and 7.2 Hz (mean 2 Hz) and decreased to a me an of 0.3 Hz 4 min after nerve lesion. C fibres displaying initial dis charge frequencies of greater than or equal to 2 Hz ceased to generate action potentials significantly sooner than those with initial discha rge frequencies of <2 Hz.