Sulfur dioxide derivatives modulation of high-threshold calcium currents in rat dorsal root ganglion neurons.
This study addressed the effect of sulfur dioxide (SO(2)) derivatives on high-voltage-activated calcium currents (HVA-I(Ca)) in somatic membrane of freshly isolated rat dorsal root ganglion (DRG) neurons by using the whole-cell configuration of patch-clamp technique. High-threshold Ca(2+) channels are highly expressed in small dorsal root ganglion neurons. SO(2) derivatives increased the amplitudes of calcium currents in a concentration-dependent and voltage-dependent manner. The 50% enhancement concentrations (EC(50)) of SO(2) derivatives on HVA-I(Ca) was about 0.4 microM. In addition, SO(2) derivatives significantly shifted the activation and inactivation curve in the depolarizing direction. Parameters for the fit of a Boltzmann equation to mean values for the activation were V(1/2)=-17.9+/-1.3 mV before and -12.5+/-1.1 mV after application 0.5 microM SO(2) derivatives 2 min (P<0.05). The half inactivation of HVA-I(Ca) was shifted 9.7 mV to positive direction (P<0.05). Furthermore, SO(2) derivatives significantly prolonged the slow constant of inactivation, slowed the fast recovery but markedly accelerated the slow recovery of HVA-I(Ca) from inactivation. From HP of -60 mV 0.5 microM SO(2) derivatives increased the amplitude of HVA-I(Ca) with a depolarizing voltage step to -10 mV about 54.0% in small DRG neurons but 33.3% in large DRG neurons. These results indicated a possible correlation between the change of calcium channels and SO(2) inhalation toxicity, which might cause periphery neurons abnormal regulation of nociceptive transmission via calcium channels.
Du
Zhengqing
Z
Shanxi University of Finance & Economics, Taiyuan 030006, PR China. duzhengqing@sxu.edu.cn <duzhengqing@sxu.edu.cn>
Meng
Ziqiang
Z
D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D013458:Sulfur Dioxide / Q000633:toxicity*
D000393:Air Pollutants; D015220:Calcium Channels; D013458:Sulfur Dioxide