Sensitization of dural afferent nerve endings modulates high voltage active calcium currents of primary sensory neurons

Objective To investigate the modulation of sensitization of dural afferent nerve endings on high voltage active calcium currents (HVA-ICa) of primary sensory neurons from rat trigeminal ganglion. Methods Male adult SD rats were randomly divided into normal saline treatment group (NS,n=8) and proinflammatory agent plus calcitontin gene-related peptide infusion group (IS+CGRP,n=8).One h after the infusion,the effect of CGRP on currents of voltage-gated calcium channel (VGCC) in neurons acutely isolated from trigeminal ganglion was recorded using a conventional whole-cell recording patch clamp technique. Results The peak level of calcium current in the IS+CGRP group ( [-80.48±4.43] pA/pF) was significantly increased as compared with that in the NS group ([-49.5±5.18] pA/pF); the half-activation voltage (Va1/2) in the activation curve of calcium current in the IS+CGRP group ([-20.9±0.4] mV) moved 4.7 mV to the hyperpolarization direction as compared with that in the NS group ([-16.2±0.5] mV) with significant difference (P＜0.05); the half-inactivation voltage (Vi1/2) in the activation curve of calcium current in the IS+CGRP group ([-12.4±0.2] mV) moved 10.1 mV to the depolarization direction as compared with that in the NS group ([-22.5 ±0.3] mV) with significant difference (P＜0.05). Conclusion Sensitization of dural afferent nerve endings facilitates peripheral sensitization of primary sensory neurons, with an outstanding performance as increment of calcium current. Key words: Migraine; Peripheral sensitization; Whole cell recording patch clamp; Calcium current