Frangez R, Meunier F, Molgo J, Suput D
Veterinary Faculty, Clinic of Obstetrics and Gynaecology, School of Veterinary Medicine, Ljubljana, Slovenia.
Pflugers Arch. 2000;439(3 Suppl):R100-1.
Equinatoxin II (EqT II) is a basic 20 kD protein isolated from the sea anemone Actinia equina. Intravenous injection of 3 LD50 of EqT II causes cardiorespiratory arrest. The aim of our study was to check the effects of EqT II on neuronal cells to assess the role of neuronal mechanisms in respiratory arrest after intravenous injection of the toxin. Effects of EqT II on mouse neuroblastoma x rat glioma NG108-15 cell were studied using confocal laser scanning microscopy and by Fura-2 fluorescence measurements. The results show that EqT II applied in nanomolar range increases intracellular Ca2+ activity significantly, which is possibly responsible for the morphological changes of NG108-15 cells after the exposure to 10 nM EqT II. Intracellular increase in Ca2+ activity can not be prevented by use of the various pharmacological substances (e.g. Ca2+ channels blocker Verapamil and Bekanamycin). Swelling of the NG108-15 cells after the exposure to the EqT II also can not be blocked with the sodium channel blocker tetrodotoxin. Increase in the intracellular Ca2+ activity is probably a result of Ca2+ entry through pores produced by the toxin, which has been shown by other authors on other cells and on phospholipid bilayer. Respiratory arrest after intravenous injection of the toxin can be caused by the action of the toxin on neuronal cells in medulla oblongata provided that EqT II can damage blood brain barrier thus enabling access to the neuronal cells. The results allow the conclusion that EqT II can affect normal calcium homeostasis and cell morphology of neuronal cells that can disturb cell physiology and its function thus affecting normal respiratory pattern.
海葵毒素II（EqT II）是一种从海葵（Actinia equina）中分离出的20 kD碱性蛋白。静脉注射3倍半数致死剂量（LD50）的EqT II会导致心肺骤停。我们研究的目的是检测EqT II对神经元细胞的影响，以评估静脉注射该毒素后神经元机制在呼吸骤停中的作用。使用共聚焦激光扫描显微镜和Fura-2荧光测量法研究了EqT II对小鼠神经母细胞瘤×大鼠胶质瘤NG108-15细胞的影响。结果表明，纳摩尔浓度范围的EqT II能显著增加细胞内Ca2+活性，这可能是NG108-15细胞在暴露于10 nM EqT II后形态变化的原因。使用各种药理物质（如Ca2+通道阻滞剂维拉帕米和贝卡霉素）无法阻止细胞内Ca2+活性的增加。暴露于EqT II后的NG108-15细胞肿胀也不能被钠通道阻滞剂河豚毒素阻断。细胞内Ca2+活性的增加可能是由于Ca2+通过毒素产生的孔进入细胞内，其他作者在其他细胞和磷脂双分子层上也有过类似发现。如果EqT II能破坏血脑屏障从而进入神经元细胞，那么静脉注射该毒素后的呼吸骤停可能是毒素作用于延髓神经元细胞所致。研究结果表明，EqT II可影响神经元细胞正常的钙稳态和细胞形态，进而干扰细胞生理及其功能，从而影响正常呼吸模式。
