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The delayed depolarization in rat cutaneous afferent axons is reduced following nerve transection and ligation, but not crush: Implications for injury‐induced axonal NA + channel reorganization
Author(s) -
Sakai Jun,
Honmou Osamu,
Kocsis Jeffery D.,
Hashi Kazuo
Publication year - 1998
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199808)21:8<1040::aid-mus8>3.0.co;2-8
Subject(s) - depolarization , sural nerve , anatomy , axon , chemistry , nerve injury , crush injury , free nerve ending , neuroscience , medicine , anesthesia , biology , surgery
Two distinct populations of Na + channels (kinetically fast and slow) are present on the cell bodies and axons of cutaneous afferent neurons; the fast current is increased and the slow current reduced in amplitude following nerve injury. The present study was undertaken to determine if similar changes occur on the axons of these neurons following peripheral nerve injury. The compound action potentials from rat sural nerves were recorded in a sucrose gap chamber. Following application of 4‐aminopyridine, a prominent and well‐characterized depolarization (the delayed depolarization) followed the action potential. This potential, only present on cutaneous afferent axons, has been correlated with activation of a slow Na + current. The delayed depolarization was reduced after nerve transection. The refractory period of transmission of the action potential was shortened in the transected nerves, but that of the delayed depolarization was prolonged. The changes were largest when the sural nerve was cut and ligated [control: 38.1 ± 1.7% ( n = 5); injury: 24.5 ± 2.8% ( n = 5), P < 0.05], which prevented reconnection to its peripheral target. When the nerve was crushed and allowed to reestablish peripheral target connections, the delayed depolarization was minimally effected. These results indicate that the changes in Na + channel organization following peripheral target disconnection observed on cutaneous afferent cell bodies also occur on their axons. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1040–1047, 1988.