Pappone P A, Cahalan M D
Department of Animal Physiology, University of California, Davis 95616.
J Neurosci. 1987 Oct;7(10):3300-5. doi: 10.1523/JNEUROSCI.07-10-03300.1987.
We have examined the effects of venom from the scorpion Pandinus imperator on the membrane currents of voltage-clamped frog myelinated nerve fibers using the Vaseline-gap method. Crude venom, applied externally in concentrations from 50 to 500 micrograms/ml, selectively blocked the voltage-gated potassium currents without affecting nodal sodium currents or resting conductances. Block of potassium channels by Pandinus venom was highly dependent on the membrane voltage, being greater at negative potentials than at positive potentials. The blocking effects of Pandinus venom were irreversible on the time scale of our experiments; however, even high concentrations of venom failed to block potassium currents completely at positive potentials. These results suggest that Pandinus venom contains a component(s) that interacts specifically and strongly with a subpopulation of axonal potassium channels.
我们使用凡士林间隙法研究了帝王蝎毒液对电压钳制的青蛙有髓神经纤维膜电流的影响。粗毒液以50至500微克/毫升的浓度外用，选择性地阻断电压门控钾电流，而不影响节点钠电流或静息电导。帝王蝎毒液对钾通道的阻断高度依赖于膜电压，在负电位时比正电位时更强。在我们的实验时间尺度上，帝王蝎毒液的阻断作用是不可逆的；然而，即使是高浓度的毒液在正电位时也不能完全阻断钾电流。这些结果表明，帝王蝎毒液含有一种与轴突钾通道亚群特异性且强烈相互作用的成分。
