BmTx3B, a novel scorpion toxin from Buthus martensi Karsch, inhibits delayed rectifier potassium current in rat hippocampal neurons.
OBJECTIVE
To examine the effect of BmTx3B, a novel short-chain peptide isolated from the venom of Asian scorpion Buthus martensi Karsch, on voltage-gated potassium channels.


METHODS
Two types of voltage-dependent potassium currents were recorded from dissociated hippocampal neurons of neonatal rat in whole-cell voltage-clamp mode, and separated based upon their kinetic properties.


RESULTS
BmTx3B (10-100 micromol/L) selectively inhibited the delayed rectifier potassium current (I(K)), without affecting the fast transient potassium current (I(A)). The inhibition of the peptide on I(K) was reversible, concentration-dependent and voltage-independent. BmTx3B did not affect the steady-state activation and inactivation kinetics of the current.


CONCLUSIONS
The short-chain scorpion peptide BmTx3B selectively blocked the delayed rectifier potassium channel.
Li
Ming-Hua
MH
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China.
Wang
Yue-Feng
YF
Chen
Xue-Qin
XQ
Zhang
Nai-Xia
NX
Wu
Hou-Ming
HM
Hu
Guo-Yuan
GY
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D051668:Delayed Rectifier Potassium Channels; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D008419:Materia Medica / Q000302:isolation & purification / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D017207:Rats, Sprague-Dawley; D012604:Scorpion Venoms / Q000302:isolation & purification / Q000494:pharmacology*; D012605:Scorpions / Q000737:chemistry
C488230:BmTx3B, Buthus; D051668:Delayed Rectifier Potassium Channels; D008419:Materia Medica; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms