BmTx3B, a novel scorpion toxin from Buthus martensi Karsch, inhibits delayed rectifier potassium current in rat hippocampal neurons.

Acta Pharmacol Sin

State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China.

Published: October 2003

Aim: 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.

Conclusion: The short-chain scorpion peptide BmTx3B selectively blocked the delayed rectifier potassium channel.

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