Changes in high voltage-activated calcium current in dorsal root ganglion neurons isolated from rats with neuropathic pain / 中华麻醉学杂志

ABSTRACT

Objective To investigate the changes in high voltage-activated (HVA) calcium current in dorsal root ganglion (DRG) neurons isolated from rats with neuropathic pain. Methods Pathogen-free male SD rats aged 4-6 weeks weighing 180-220 g were used in this study. The animals were anesthetized with intraperitoneal pentobarbital sodium 50 mg/kg. Neuropathic pain was induced by ligation of L5 spinal nerve between DRG and sciatic nerve. The nerve was transected distal to the ligature. The animals which showed positive signs of neuropathic pain were decapitated on the 14th postoperative day. L5 and L4 DRGs were isolated and the neurons in the ganglia were enzymatically dissociated (group L5 and L4). The control group received no surgery (group C). The HVA Ca2+ current was recorded using whole-cell patch clamp technique. Results Peak calcium current density was significantly lower in group L5 and L4 than in group C, and was significantly lower in group L5 than in group L4 . Halfactivation value (Va 1/2) was also significantly lower in group L5 than in group C and L4 (P ＜ 0.05). The relative contribution of N-type to the total HVA Ca2+ current was significantly greater in group L5 than in group C and L4(P ＜ 0.05). There was no significant difference in the steady-state inactivation curves among the 3 groups. Conclusion In rats with neuropathic pain, the HVA Ca2+ current in the injured DRG neurons may play a key role in the induction of neuropathic pain.