Inceoglu Bora, Lango Jozsef, Jing Jie, Chen Lili, Doymaz Fuat, Pessah Isaac N, Hammock Bruce D
Department of Entomology, Chemistry and Superfund Analytical Laboratory, Molecular Biosciences, School of Veterinary Medicine, and Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA.
Proc Natl Acad Sci U S A. 2003 Feb 4;100(3):922-7. doi: 10.1073/pnas.242735499. Epub 2003 Jan 27.
Scorpion venom is a complex mixture of salts, small molecules, peptides, and proteins. Scorpions employ this valuable tool in several sophisticated ways for subduing prey, deterring predators, and possibly during mating. Here, a subtle but clever strategy of venom utilization by scorpions is reported. Scorpions secrete a small quantity of transparent venom when initially stimulated that we propose to name prevenom. If secretion continues, a cloudy and dense venom that is white in color is subsequently released. The prevenom contains a combination of high K(+) salt and several peptides including some that block rectifying K(+) channels and elicit significant pain and toxicity because of a massive local depolarization. The presence of high extracellular K(+) in the prevenom can depolarize cells and also decrease the local electrochemical gradient making it more difficult to reestablish the resting potential. When this positive change to the K(+) equilibrium potential is combined with the blockage of rectifying K(+) channels, this further delays the recovery of the resting potential, causing a prolonged effect. We propose that the prevenom of scorpions is used as a highly efficacious predator deterrent and for immobilizing small prey while conserving metabolically expensive venom until a certain level of stimuli is reached, after which the venom is secreted.
蝎毒是盐类、小分子、肽类和蛋白质的复杂混合物。蝎子以多种复杂方式利用这种宝贵工具来制服猎物、威慑捕食者，可能还会在交配时使用。在此，报道了蝎子利用毒液的一种微妙而巧妙的策略。蝎子在最初受到刺激时会分泌少量透明毒液，我们提议将其命名为前毒。如果分泌持续，随后会释放出浑浊且浓稠的白色毒液。前毒含有高钾盐和几种肽的组合，其中一些肽会阻断整流钾通道，并由于大量局部去极化而引发显著的疼痛和毒性。前毒中高细胞外钾的存在会使细胞去极化，还会降低局部电化学梯度，使得重新建立静息电位更加困难。当钾平衡电位的这种正向变化与整流钾通道的阻断相结合时，会进一步延迟静息电位的恢复，产生延长效应。我们认为，蝎子的前毒被用作一种高效的捕食者威慑手段，用于固定小型猎物，同时保存代谢成本高昂的毒液，直到达到一定程度的刺激，之后才分泌毒液。
