The modulation effects of BmK I, an alpha-like scorpion neurotoxin, on voltage-gated Na(+) currents in rat dorsal root ganglion neurons.
The present study investigated the effects of BmK I, a Na(+) channel receptor site 3 modulator purified from the Buthus martensi Karsch (BmK) venom, on the voltage-gated sodium currents in dorsal root ganglion (DRG) neurons. Whole-cell patch-clamping was used to record the tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) components of voltage-gated Na(+) currents in small DRG neurons. It was found that the inhibitory effect of BmK I on open-state inactivation of TTX-S Na(+) currents was stronger than that of TTX-R Na(+) currents. In addition, BmK I exhibited a selective enhancing effect on voltage-dependent activation of TTX-S currents, and an opposite effect on time-dependent activation of TTX-S and TTX-R Na(+) currents. The results suggested that the inhibitory effect of BmK I on open-state inactivation might contribute to the increase of peak TTX-S and TTX-R currents, and the enhancing effect of BmK I on time-dependent activation might also contribute to the increase of peak TTX-S currents. It was further suggested that a combined effect of BmK I including inhibiting the inactivation of TTX-S and TTX-R channels, accelerating activation and decreasing the activation threshold of TTX-S channels, might produce a hyperexcitability of small DRG neurons, and thus contribute to the BmK I-induced hyperalgesia.
Chen
Jin
J
Graduate School of the Chinese Academy of Sciences, Shanghai Institute of Physiology, Institutes for Biological Sciences, Chinese Academy of Sciences, PR China.
Tan
Zhi-Yong
ZY
Zhao
Rong
R
Feng
Xing-Hua
XH
Shi
Jian
J
Ji
Yong-Hua
YH
D000818:Animals; D005727:Ganglia, Spinal / Q000166:cytology*; D015640:Ion Channel Gating; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011042:Poisons / Q000378:metabolism; D051381:Rats; D012604:Scorpion Venoms / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism*; D013779:Tetrodotoxin / Q000378:metabolism
D011042:Poisons; D012604:Scorpion Venoms; D015222:Sodium Channels; C105338:makatoxin I; D013779:Tetrodotoxin