Blaustein M P, Rogowski R S, Schneider M J, Krueger B K
Department of Physiology, University of Maryland School of Medicine, Baltimore 21201.
Mol Pharmacol. 1991 Dec;40(6):932-42.
Venoms from five Old World and two New World scorpions were tested for their ability to block various K+ channels in rat brain synaptosomes. A 86Rb efflux kinetic assay was used to identify three types of K+ channels, Ca(2+)-independent, voltage-gated, inactivating (A-type) and noninactivating (delayed rectifier) K+ channels and Ca(2+)-activated K+ channels [J. Physiol. (Lond.) 361:419-440, 441-457 (1985)]. The venoms from the Old World scorpions all blocked the A-type K+ channel but not the delayed rectifier K+ channel; only venom from the Israeli scorpion, Leiurus quinqestriatus hebraeus (Lqh), blocked the Ca(2+)-activated K+ channel. In contrast, venoms from the two New World scorpions selectively blocked the delayed rectifier K+ channel. Water-soluble components from Lqh venom from the Brazillian scorpion, Tityus serrulatus (Ts), were separated by ion exchange high performance liquid chromatography (HPLC). Seven components that blocked synaptosome K+ channels were isolated from Lqh venom by ion exchange HPLC. All seven components blocked the A-type K+ channel; the five most potent toxins had IC50 values of 18-40 nM. Two of the components from Lqh venom (one identified as charybdotoxin and the other denoted as Lqk4) also blocked a Ca(2+)-activated K+ channel (IC50 = 15 and 60 nM for charybdotoxin and Lqk4, respectively). Five K+ channel-blocking components were isolated from the Ts venom; all five blocked the delayed rectifier channel selectively, and the two most potent components had IC50 values of 8 and 30 nM. Several of the more potent Lqh and Ts toxins were purified to near-homogeneity by reverse phase HPLC. These toxins should be useful as ligands for K+ channel purification, for elucidation of K+ channel structure, and for studies of K+ channel function.
对来自五个东半球和两个西半球蝎子的毒液进行了测试，以检测它们阻断大鼠脑突触体中各种钾离子通道的能力。采用⁸⁶Rb外流动力学测定法来鉴定三种类型的钾离子通道，即钙非依赖性、电压门控、失活型（A 型）和非失活型（延迟整流器型）钾离子通道以及钙激活钾离子通道[《生理学杂志》（伦敦）361:419 - 440, 441 - 457 (1985)]。东半球蝎子的毒液均能阻断 A 型钾离子通道，但不能阻断延迟整流器型钾离子通道；只有来自以色列蝎子以色列金蝎（Leiurus quinqestriatus hebraeus, Lqh）的毒液能阻断钙激活钾离子通道。相比之下，两个西半球蝎子的毒液则选择性地阻断延迟整流器型钾离子通道。通过离子交换高效液相色谱法（HPLC）分离了来自巴西蝎子锯齿脂鲤蝎（Tityus serrulatus, Ts）的 Lqh 毒液的水溶性成分。通过离子交换 HPLC 从 Lqh 毒液中分离出七种能阻断突触体钾离子通道的成分。所有七种成分均能阻断 A 型钾离子通道；五种最有效的毒素的半数抑制浓度（IC₅₀）值为 18 - 40 nM。Lqh 毒液中的两种成分（一种鉴定为蝎毒素，另一种命名为 Lqk4）也能阻断钙激活钾离子通道（蝎毒素和 Lqk4 的 IC₅₀分别为 15 和 60 nM）。从 Ts 毒液中分离出五种钾离子通道阻断成分；所有五种成分均选择性地阻断延迟整流器通道，两种最有效的成分的 IC₅₀值为 8 和 30 nM。通过反相 HPLC 将几种更有效的 Lqh 和 Ts 毒素纯化至接近均一性。这些毒素可作为钾离子通道纯化的配体、用于阐明钾离子通道结构以及研究钾离子通道功能。
