Tauc M, Gastineau M, Poujeol P
Département de Biologie cellulaire et moléculaire, CEN Saclay, Gif sur Yvette, France.
Biochim Biophys Acta. 1992 Mar 23;1105(1):155-60. doi: 10.1016/0005-2736(92)90174-k.
The effects of Leiurus quinquestriatus hebraeus (LQH) venom, mamba venom, Buthus tamulus (BT) venom, purified apamin and synthetic charybdotoxin on the membrane hyperpolarization induced by extracellular ATP were examined in Madin-Darby canine kidney cells. For this we used a membrane potential probe (bisoxonol) to determine the potential variations. The relation between bisoxonal fluorescence and membrane potential was established by treating Madin-Darby canine kidney cells suspended in solutions containing various external sodium concentrations with gramicidin. Extracellular ATP induced a rapid hyperpolarization that was blocked by LQH venom and synthetic charybdotoxin. BT venom also blocked the response but at a much higher concentration than that of LQH. Mamba venom (Dendroaspis polylepis) and apamin did not modify the ATP-induced hyperpolarization. We concluded that the ATP induced hyperpolarization was due to the augmentation of the potassium conductance probably through Ca(2+)-activated K+ channels sensitive to charybdotoxin but not to mamba venom. The interaction previously described between charybdotoxin and dendrotoxin (the main toxin of mamba venom) was not observed in our case.
在麦迪逊-达比犬肾细胞中，研究了以色列金蝎（LQH）毒液、曼巴蛇毒液、印度红蝎（BT）毒液、纯化的蜂毒明肽和合成的蝎毒素对细胞外ATP诱导的膜超极化的影响。为此，我们使用膜电位探针（双羟萘酚）来测定电位变化。通过用短杆菌肽处理悬浮在含有不同外部钠浓度的溶液中的麦迪逊-达比犬肾细胞，建立了双羟萘酚荧光与膜电位之间的关系。细胞外ATP诱导快速超极化，该超极化被LQH毒液和合成的蝎毒素阻断。BT毒液也阻断了该反应，但所需浓度比LQH高得多。曼巴蛇毒液（黑曼巴蛇）和蜂毒明肽未改变ATP诱导的超极化。我们得出结论，ATP诱导的超极化可能是由于钾电导增加，这可能是通过对蝎毒素敏感但对曼巴蛇毒液不敏感的钙激活钾通道实现的。在我们的实验中未观察到先前描述的蝎毒素与树突毒素（曼巴蛇毒液的主要毒素）之间的相互作用。
