Lev-Ram V, Olivera B M, Levitan I B
Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.
Brain Res. 1994 Mar 21;640(1-2):48-55. doi: 10.1016/0006-8993(94)91856-2.
Conus textile crude venom and a peptide component ('King Kong' toxin) purified from this venom, alter membrane excitability of Aplysia neurons. Venom, applied to the medium bathing an abdominal ganglion, changes dramatically the electrical activity of bursting pacemaker neuron. The effects on bursting neuron R15 was examined in current-clamp and voltage-clamp modes. A dual phase effect of both the venom and the purified toxin were observed. The first phase starts immediately after venom or toxin application and is observed as an increase in membrane excitability, resulting in an enhancement of bursting. The second phase begins about 15 min later and consists of a long-lasting hyperpolarization. The dual phase effect of the venom and the toxin persists even when synaptic input is eliminated either by axotomy, or by recording from freshly dissociated neurons or from neurons in primary cell culture. The ionic currents affected are an inward current, INSR, which is activated upon depolarization and an anomalously rectifying potassium current, IR, which is activated upon hyperpolarization. In the first phase of toxin action INSR is increased. In the second phase both the venom and the toxin block INSR and increase IR. The toxin effects may be due to complex alteration of one or more second messenger cascades rather than a direct action on ion channels.
芋螺毒素粗毒液以及从该毒液中纯化得到的一种肽成分（“金刚”毒素）会改变海兔神经元的膜兴奋性。将毒液施加到浸泡腹神经节的培养液中，会显著改变爆发性起搏神经元的电活动。在电流钳和电压钳模式下研究了其对爆发性神经元R15的影响。观察到毒液和纯化毒素均有双相效应。第一相在施加毒液或毒素后立即开始，表现为膜兴奋性增加，导致爆发增强。第二相大约在15分钟后开始，表现为持久的超极化。即使通过切断轴突、从新解离的神经元或原代细胞培养中的神经元进行记录来消除突触输入，毒液和毒素的双相效应仍然存在。受影响的离子电流包括一个内向电流INSR，它在去极化时被激活，以及一个反常整流钾电流IR，它在超极化时被激活。在毒素作用的第一阶段，INSR增加。在第二阶段，毒液和毒素都会阻断INSR并增加IR。毒素的作用可能是由于一个或多个第二信使级联反应的复杂改变，而不是对离子通道的直接作用。
