Novel purinergic sensitivity develops in injured sensory axons following sciatic nerve transection in rat

Teased fibers were made from 153 spontaneous A afferents ending in sciatic nerve end neuromas of 3-14 days standing, 21 A afferents from intact sensor y endings in the contralateral sciatic nerve, and 50 intact A afferents fro m the sciatic nerve in intact rats. Ninety-two percent of the injured fiber s responded to adenosine 5'-triphosphate (ATP) (i.v.). However, few fibers from the contralateral nerve or nerves from intact animals responded to ATP . P2 receptor antagonist suramin or reactive blue 2 blocked the ATP-induced response in 76% of the fibers tested, whereas the P1 receptor antagonist a minophylline blocked the ATP-evoked effect in only 18% of the fibers tested . Sympathectomy did not affect the ATP-induced effects in injured axons. Cl ose-arterial injection of ATP caused similar results as i.v. injection of A TP. The present study suggests that a novel purinergic sensitivity is devel oped at the injury site after sciatic nerve transection in rats, which may play a role in neuropathic pain under some conditions such as sympathetic a ctivation. (C) 2001 Elsevier Science BY. All rights reserved.